31 Koi Diseases (and their Treatments)

This article describes dozens of koi diseases as well as the most appropriate treatments. The sooner you can diagnose, the sooner you can treat.

Its probably not surprise but for a koi, life can be full of peril. The fish in an outdoor pond are subject to not only birds of prey and raccoon but to things you often can’t see that live in your water and infect your fish.

Fortunately, there is a great deal of information on koi diseases and an equal amount of treatments but the most important thing is being informed on those diseases. The more you know about diseases of koi, the better you can treat them.

Listed below are most of the more common koi diseases and the best treatments.

Ich

One of the most common diseases found in Koi is Ich (aka; White Spot disease). It is a protozoan that begins its growth in the pond and later attaches to the gills of the Koi as it matures.

The ich parasite initially appears like little white grains of salt on your Koi. Ich can kill smaller Koi, especially in crowded ponds and can cause other bacterial infections in your fish.  It is usually borne out of poor water quality so to deal with the disease at its root, proper water chemistry will have to be achieved.

Tropical fish specialists frequently deal with Ich. It can, however, also infect cold water fish. They must attach to the fish within 48 hours of hatching or they will die. Once they attach themselves to fish, they dig into the skin and feed on the fish’s tissue.

After feeding on the fish for approximately three weeks, they detach themselves and move to the bottom of the pond to reproduce. The Ich hatch out of cysts at the bottom of the pond and use small hair-like tentacles called cilia to swim about.

Treating Ich

There are a couple of widely used methods to treat ich. The first one requires the koi owner to increase the salt concentration of the pond or quarantine tank to about 0.5% over a period of days. At the same time increase the temperature of the water gradually to the mid 80’s F while increasing aeration. 

This quarantine should last 2 weeks and is an effective and cheaper way to deal with the ich protozoan. The second method is a tried and true method for dealing with parasites in general and involves malachite green and formalin.

Using both simultaneously is definitely going to be effective against ich but you may be able to simply treat with malachite green alone.

For short treatments in quarantine, one could do a quantity of 1.5 mg of malachite green for every liter of water for up to 1 hour (or 6mg of malachite green for every gallon of water). Always wear gloves when handling both malachite green and formalin.

Dropsy (Pinecone Disease)

Fish that have dropsy often show signs of swelling or lifting of the scales. Their eyes will frequently bulge. If you ever notice this, don’t hesitate to separate the infected fish from the others. Paying careful attention to your fish in order to notice these symptoms as early as possible means that your other fish stand a better chance of surviving.

Treating Dropsy

Dropsy is, more or less, terminal. By the time you see your fish bloated with standing scales it means that there is kidney and liver failure.  Prevention of infection to your other fish is recommended with MedFinn or Debride RX. 

Tail Rot

Tail rot and fin rot are really secondary to the original problem which could be stress or poor water quality that is causing your koi to be immuno-compromised in the first place. Once they are weakened then the already-present bacteria can move in a cause physical damage to your koi’s fins.

Treating Tail Rot

One good start to treating this malady is by a 30 -50% water change of your pond. Using Mela-Fix is also a great option for dealing with the bacteria themselves and you can also add salt to your pond which will go to work on your bacteria and also lower stress levels for your koi. If you’d like you can also feed them MedFinn (just as with the cloudy eye treatment).

Mouth Rot

Mouth rot is a symptom of something larger and that is usually poor water quality that is causing your fish’s health to be compromised and open to infection. You’re going to want to stop feeding for the time being and start improving your water quality by doing a 30% water change.

Next thing would be a light salt bath treatment and perhaps a treatment of Mela-Fix. You will also want to monitor your water quality by testing it regularly. You can also remove the fish and treat the sores with hydrogen peroxide or iodine.

Chilodonella 

Some of the symptoms included with this protozoan parasite are: dying on the surface and rolling over on the fish’s s sides. This is a notorious killer of koi.

Treating Chilodonella 

You will want to increase the salt concentration in the pond for 2 weeks as well as increasing aeration.

Aeromonas Bacteria

These bacteria are associated with ulcers and fin erosion.

Treating Aeromonas 

The koi will need to get injections of Chloramphenicol.  This treatment should yield positive results in 3-4 days.

Pseudomonas bacteria 

Like its cousin, aeromonas, this bacteria is also associated with ulcers and fin erosion.

Treating Pseudomonas 

Infections of this nature will require an injection of Baytril.

Columnaris 

This bacteria will attack sites of injury but will cause fin, tail and mouth rot.  Additionally fish can be vulnerable to it during times of stress. 

Your fish may develop a white film on their skin and display sunken in eyes.  It can be a rapid killer so be sure to take swift action.

Treating Columnaris 

Feeding your koi MedFinn or Debride RX will definitely help your fish with an “inside out” treatment strategy. 

Anchor worm (Lernea)

Anchor worm, also known as Lernea is a crustacean parasite that attaches to, and digs into the skin of fish. The female Lernea attaches to fish while males do not. The worm feeds on the fish, damaging its tissue.

This leads to a bacterial and/or fungal infection on the fish. Another crustacean parasite, Argulus also attaches itself to fish and causes damage to tissue.

Treating Anchor Worm 

They can be removed using tweezers or other small pincers. After removal, rub some Neosporin on the infected area. Use Dimilin, Dylox or Lufenuron to treat the pond. 

Though Dimilin is probably your best bet for clearing up anchor worm there are other products out there that have a good track records as well and those include ECORX and Anchors Away.

Argulus (Fish Lice)

These unwanted invaders have eight legs and rounded bodies. They also have to big suckers which are used to attach to the fish. Their appearance leads to their nickname, “fish lice”.

These parasites can cause considerable irritation to fish and can lead to bacterial infections.  The irritation will lead to flashing and rubbing which should tip you off that something is wrong and the koi are trying to get some relief.

Treating Argulus  

As with anchor worm, treatment will consist of Dimilin but another product also works as well, Lufenuron.  You should see positive results in a matter of days.

Fungus

Mild or moderate infections can be treated and possibly cured if they are caught early. These types of fungal infections are not typically contagious and usually only a single Koi becomes infected.  

Fungal infections in fish almost always begin externally and start through a break in the outer skin layer of the fish. Affected Koi usually display fluffy or cotton-like growths on their skin.

These growths may also exhibit a green tinge because of algae growth on the fungus. There may also be raised white, brown, yellow or green irregular bumps seen on the fish’s fins. Most infections can be successfully treated if caught early so it is important to visually inspect your fish frequently.

Treating Fungus 

If the water temperatures are cold its most likely fungus however epistylis is also a possibility.  Fungus can be removed by gently rubbing the area with a cotton swab while the infected area must be treated with an antibiotic or antimicrobial cream immediately afterwards.  

If you are not sure if its fungus or epistylis try raising the salinity of the pond or quarantine tank- fungus won’t be negatively affected by salt but epistylis will.

Lymphocystis

Your Koi fish may have Lymphocystis if its displaying any buff discoloration on its skin. Another sign of Lymphocystis is rough, raised lesions on its skin. 

Though not typically contagious or fatal it is can be disfiguring to the fish carrying this virus.  This condition often occurs when the water temperature in the fish’s environment has changed. 

Treating Lymphocystis 

You will want to put the infected fish in a quarantine tank and increase the heat.  There is a treatment containing “neutral acriflavine” that will help defeat the virus (this product takes the brand name “Lymphocystis Cure”). 

It is entirely possible and not uncommon for the virus to go away on its own.

Epistylis

This is an uncommon parasitic infection that is dangerous and can cause other diseases in your Koi. It is usually caused by poor management of the water, resulting in dirty water infected with parasites.

If you do not regularly change the water in the pond, it can easily become a host to these parasites. Epistylis looks like a fungus and thrives in ulcers and wounds on Koi fish.

You can identify an infected fish if you see white colored tufts in and around ulcers and wounds on the fish’s skin.

Treating Epistylis 

Change the water in the pond and add salt (0.3% concentration) to combat these parasites.  One can also put the affected fish in quarantine for 2 weeks while raising salt levels to 0.3%.

Its always nice to have a comprehensive reference manual you can look at when concerned about your koi’s health. My “go to” manuals are the Manual of Koi Health and Koi Health and Disease (Ed. 2). Edition 2 of “Koi Health and Disease” is supposed to be much more comprehensive than the first edition (the one I own) plus it has quick reference charts for disease diagnosis and its spiral bound for ease of use.

Koi Health & Disease: Everything You Need To Know 2nd Edition

Fish normally eat less during the winter and by eating less, fish tend to lose a bit of weight. This normal change sometimes masks Skinny disease.

Skinny Disease

The disease is caused by a bacterial infection that causes the fish to have a sucked-in gill appearance. Its head will often appear much bigger than the rest of its body.

Treating Skinny Disease 

Adding extra food to the fish’s diet can usually clear up this disease. However, sometimes this doesn’t help and if the bacterial infection persists, adding erythromycin to the fish’s food normally clears the infection up quickly.

Carp Pox

Similar in nature to Lymphocystis, carp pox is common, not very contagious, not usually fatal  but can disfigure.  Unlike its cousin, this virus causes soft and waxy looking raised growths. They are often described as being like pinkish, melted wax on the koi’s skin.

Treating Carp Pox 

There is no effective treatment for this virus but fortunately it usually goes away on its own.  Gradually heating the water may expedite the virus diminishing.  For some pond owners this is just something that shows up every winter and spring and goes away with the onset of summer.

Spring Viremia of Carp (SVC)

As the name suggests, this viral disease likes cold water and shows up in spring when the water is still cold and your koi’s immune system is not in full swing.  Some of the symptoms that you may see are a reddening of the skin and swim bladder inflammation. 

It isn’t usually a primary disease as it will normally only come in after another debilitating affliction like a bacterial infection distresses the fish.  Fortunately, SVC is not usually fatal.

Hexamita

This disease also known as “hole in the head” disease is protozoan parasite responsible for lesions in the dermal layers of koi.  You will notice your koi being lethargic and, more definitively, you will notice an erosion of the skin (and usually the fins as well). 

Your koi will isolate themselves in a given area of the pond and, as a result of the disease, will darken in color.

Treating Hexamita 

As with many diseases, you will want to quarantine this fish.  You will also want to establish a treatment course with a product called Flagyl for 10-12 days.

Cotton Wool Disease

Another disease Koi sometimes suffer is called Columnaris, which is sometimes also called Cotton Wool Disease. White threads in the fish’s mouth and a dry skin appearance are the main characteristics of this disease.

Sometimes the color of the Koi becomes darker and white sores can appear on its skin. It is not always easy however to determine if the fish has the fungus in its gills.

However, if the Koi stays near the surface of the pond, gulping for air, it is a good indication that the fungus is, in fact, in the gills. The Koi can also develop a soggy belly and a slimy coating over its skin.

Treating Cotton Wool 

You can put potassium permanganate in the water to help clear up the condition. Additionally, injecting antibiotics and treating the wound directly will help care for the disease.

You should separate the infected Koi from the population and treat the water so the other fish do not become infected.

Flukes

There are two main classes of flukes; 1) gill flukes and 2) skin flukes. Both kinds are microscopic so if you suspect your fish are suffering from flukes you will need a microscope to verify it.

Dactylogyrus or gill flukes will attach to the gills and, as the name suggests, body flukes or gyrodactylus attach to the body.

Having hitch hikers is usually not a problem…except if you’re a koi and they are parasitic! Flukes tend to eat away at the protective “slime” coating of your fish thereby exposing them to harmful bacterial infections and causing ulcers.

They also are an irritant and cause your fish to itch and subsequently rub themselves on the bottom or side of the pond in an attempt to itch and rid themselves of the parasite.

Gill flukes can eat away at your koi’s gills so much that the koi will not be able to assimilate oxygen from the water. If you suspect a fluke infection be sure to look out for this behavior.

Treating Flukes 

You can quarantine but it is likely that your entire pond is afflicted with the flukes or their eggs so you can treat with medications like potassium permanganate or Aquascape Praziquantel.  Some additional treatments are SupaVerm (will kill goldfish but won’t affect your beneficial bacteria) and Fluke Tabs.

Oodinium Parasites

The disease caused by these parasites is sometimes called Velvet Disease because it resembles a velvety golden dust, which covers the fish.  Other symptoms include ragged fins and a loss of scales and skin.  Though it is somewhat rare there are treatments.

Treating Oodinium

Adding salt to the pond’s water does not normally clear up Velvet Disease. The best option is to add 37% Formalin to the water as this has been shown to be most effective.  Alternatively, Simazine can also be used to treat oodinium.

Costia

Costia, like Flukes, are a parasite. In this case it is a microscopic flagellate that can reproduce rapidly. Typically koi don’t suffer from costia unless they are already compromised in some way to begin with so it would be classified as a secondary illness. 

This affliction is usually associated with spring time. Your koi will appear lethargic and will attempt to flash or rub on the sides or bottom of the pond to itch and rid themselves of the parasite.

The skin will also appear whitish/grayish on the infected are of the koi’s body and potentially reddening fins.

Though these parasites can affect the skin they will also infect the gills of your koi as well therefore you may see gasping at the surface.

Treating Costia 

There are treatment options for costia. Malachite green and 37% formalin can be used but you will need to make sure there is no salt in the pond to start with.  If this treatment is chosen be sure to increase aeration.   

As with flukes, potassium permanganate can be used to treat costia. Some practitioners will recommend a strong salt bath (up to 0.6%) while other treatments include trypaflavine which goes by the trade name Acriflavine and copper.

Copper is used because most invertebrates, like costia flagellates, have copper-based hemolymph (blood) and therefore copper as a treatment in ponds is toxic to them.

Acriflavine should be added to your pond at a rate of 1ml/liter and copper is most appropriate at 2 mg/liter. It is critical that you do not overdose with these two treatments.

Pop Eye

Pop eye is also called exophthalmia and is really not linked to any one illness but is more of a symptom of something more. It is a direct response to an excess of fluid or possibly gasses built up behind the eye which then cause the eye to bulge is distend.

There could be several things that could cause this to happen. Sometimes this malady is caused by a bacterial infection while other times it is due to trauma from running into the side of a concrete pond.

Treating Pop Eye 

The best course of action is to immediately quarantine the fish and do a light salt bath. You will also want to greatly reduce feeding and how much you give it. You will also want to do 25% water changes daily and monitor water quality on a regular basis.

Cloudy Eye

Cloudy eye is somewhat uncommon but it can occur. This malady is typically a symptom of something else going on rather than something attacking the eye specifically.

Some causes are bacterial infection, a cataract or even lack of the right kinds of foods (which is why you want to diversify their diet and feed them only quality food with less fillers).

On rare occasions the reason could be a fluke on the eye but sometimes its a simple as physical damage to the eye by running into something in the pond. Both eyes can have pop eye or just one, either is possible.

Treating Cloudy Eye 

Treatments for cloudy eye are a medicated koi food formulated to handle fungal and bacterial issues called MedFinn and or Mela-Fix. Mela-Fix is actually an oil extract from the Melaleuca tree mostly occurring in Australia and it has natural anti-bacterial properties.

Leeches

Unfortunately, leeches aren’t just looking for a free ride but also a free meal and eventually they will cause mortality of the host fish if left untreated.

Leeches can also transmit the koi disease known as SVC. If you think your koi may be victims of leeches you can actually see them on their bodies as the leeches are not microscopic but other symptoms include a darkening or paling of the color of your koi as well as lethargy.

Treating Leeches 

Some treatments for leeches include a product called Masoten which comes in powder form. Another product is called malathion however many recommend against this treatment as it is an organophosphate insecticide and though it will kill leeches it may also harm your koi in the process.

Ulcers

Ulcers on the skin of your fish result from bacterial infections that form on scales, causing them to become red. The infection causes holes, or ulcers on the exterior of the fish and will eventually result in loss of scales if left untreated.

These ulcers are most often caused by poor quality of the water in the pond coupled with depressed koi immune systems in Spring get attacked by parasites carrying bacteria.  

Ulcer Treatment 

Maintain a healthy, clean pond and treat ulcers with a topical antibacterial such as Panalog to stop the bacteria in their tracks.

Saprolegnia Fungus

One of the most common fungal infections found in Koi fish comes from the Saprolegnia fungus. Spores from the fungus can grow on any part of the fish, including its gills. The fungus first attacks the fish by germinating on dead tissue.

The fungus has thread-like hyphae that release a substance that breaks down the tissue. As the fungal infection grows, these juices begin breaking down and destroying living tissue. 

It often appears like cotton wool and may be stained green from algae.  It almost never attacks a healthy fish –typically the koi will already have some sort of breach like an ulcer.

Treating Saprolegnia

The afflicted fish will need to be isolated in a quarantine tank with the temperature raised to at least 77 degrees F.  Additionally, it will be very beneficial to also get your salt levels up to around 0.3%.

Trichodina

One of the easiest protozoan parasites to see under a microscope, and subsequently confirm your fish is infected, is Trichodina. An infection of this parasite can be detected by a gray-white opaque appearance on the body of infected Koi.

Trichodina is a warm water parasite and can survive in the water for a considerable amount of time without a host.

Visually, they are perfectly round with hundreds of little hooks that look like cilia. It rotates continuously as it moves through mucus, causing damage to the Koi’s tissue.

This parasite attacks both the skin and gills of your Koi. Infected fish also often show symptoms such as flashing, rubbing and lethargy.

Treating Trichodina 

Treat this disease with a five day course of increased salinity (0.5 to 0.6%).   Due to increasing tolerance of some organisms to salt treatments a course of formalin may be necessary.

Koi Herpes Virus (KHV)

This virus is a potent one.  Some of the effects of this disease are sloughing off of the skin which leaves the koi vulnerable to bacterial infection.  Your koi will be lethargic and have sores and lesions on its skin, gills and fins. 

Because some diseases have overlapping symptoms, gill lesions are one of the more definitive indications of KHV.  This virus is contagious and carries and high mortality rate so treatment needs to be swift.

Treating Koi Herpes Virus 

Increase salt concentration to around 0.45% and bring the water temperature up about 1 degree F every hour until it gets to 87 degrees. The fish should remain in this situation for 4 days during which medicated food such as MedFinn should be fed. 

Gill Maggots

Another parasite sometimes infecting Koi is the gill maggot. The parasite most often attacks the Koi’s gills and has a maggot-like egg sac appearance. It is a relatively uncommon parasite sometimes found in Koi ponds but when present, can cause Koi quite a bit of irritation.

You will notice the koi flashing and subsequently the gills become less efficient at absorbing oxygen. The most obvious sign of infection is seeing a Koi gasping for air at the surface of the pond.

Treating Gill Maggots 

The product Lice-Solve has been shown to be effective against gill maggots (as well as argulus) but you will need to increase aeration.  You can treat the whole pond or individual fish in quarantine.

Bent Koi

Pond owners may sometimes notice that one of their koi is taking on a bent appearance.  There may be a few explanations for this:

1) scoliosis from lack of ascorbic acid (Vit. C) in their diet

2) electrical discharge into the water and

3) internal air bladder infection  

Scoliosis can be treated by feeding your koi foods high in Vit. C like yellow bell peppers or kale.  

Electrical discharge into your pond may come from submerged pumps that are damaged or otherwise not operating properly and leaking electricity into the water -these discharges can be easily tested for.  

A swim bladder infection will most likely require antibacterial injections by someone with injection experience.

Clearly there are quite a few little “beasties” out there that can make life miserable for your koi however there are a good deal more treatments these days as opposed to say 100 years ago.

Also, because the treatments are more potent these days there is a good chance that you can deal with a disease or parasite quite rapidly and not lose your prize breeding stock -or even just your favorite koi.

As mentioned previously, the two manuals I recommend having around for quick reference on disease are:

     

General FAQ

Why is my koi laying on the bottom?

Usually a stressor such as parasites or poor water quality will prompt koi to lay on the bottom. Another reason could be low dissolved oxygen in the water causing the koi to be lethargic.

Why aren’t my koi eating?

This can be attributed to one of several things. One of them could be stress, another may be from an internal bacterial infection. As temperatures grow colder in winter, koi’s metabolism slow as does their desire for food.

Why is my koi rubbing itself on the side of the pond?

This is called “flashing” and is typically a sign that your koi has some kind of ecoparasite and is trying to rid itself of them.

Why are parts of my koi, like the tail, becoming red?

This is likely fin rot that is ultimately caused by bacteria. Usually these bacteria exist in your pond due to water quality issues.

What are the white spots on my koi?

This could be one of several things. It is commonly ich but could also be cotton wool disease or perhaps the trichodina parasite.

Why is my koi gasping at the surface?

The most common culprit is insufficient dissolved oxygen in your pond. This is easily remedied by adding an air stone at the bottom of your pond.

272 thoughts on “31 Koi Diseases (and their Treatments)”

  1. Looks like I have a fish that has a fungal infection. Got caught in the skimmer box and now has like a green coat on a part of the skin

    Reply
    • Jeff, Looks like the protective “slime” coat may be have gotten partially removed thereby inviting bacterial invasion on the skin. One solution that has worked for me in the past is a product called Mela-Fix. This product is an extract of the Melaleuca tree native to Australia and has natural anti-bacterial properties -really works great.

      Reply
  2. Not sure what has happened to my Koi, yesterday he didn’t come when I rang the dinner bell (tapping a rock with my toe). Today he was hanging out by the edge and I could see that his eyes are all clouded over otherwise he looks fine.

    Reply
    • Most likely sounds like Cloudy Eye. This is a symptom of a bacterial infection. One thing you can do is a saltwater bath or a bath in an anti-bacterial like Myxazin.

      Reply
  3. i have some small koi in a large aquarium. I will one move to my pond. Just noticed one swimming funny top fin closed and some red streaks on its body. what do you think?

    Reply
    • res streaks is most likely a symptom of higher than normal ammonia. You need better filtration and/or reduce the the amount you’re feeding your koi.

      Reply
  4. Started losing fish about two weeks ago. All displayed redness and tissue loss around the mouth noticed at feeding time. Four down, but still have 20+ I’d like to save. Pond has been in stasis for several years, but earlier this summer I introduced 1) some new fish, and 2) duckweed from a very high-nutrient outflow. Any ideas?

    Reply
    • Well I know koi will eat duckweed so under normal circumstances that shouldn’t be a problem unless the duckweed you transplanted came from water that may have somehow tainted the duckweed and subsequently sickened your fish. The other thing is that if you had no problems before then added some more fish, more fish than the system could handle then you may have a build up of ammonia from natural processes of koi metabolism. You may need to do a water change in your pond and/or a water filter cleaning. You’ll definitely want to test your water as your first step though.

      Reply
      • my koi fish is looking like it have a stones in the mouth but no it is a infaction i dont know i dont want to lose the fish i love it so much can u tell me why its like thta pleass

        Reply
  5. We have a pond of about 800-900 gallons. Have had a lot of rain lately and have started losing fish one at a time. In the past few days all the fish have started to be lethargic on the bottom and tend to have their noses to the walls. I checked ph and it is around 6-6.5; nitrates: NO2=.5; NO3=20.
    I removed a dead fish today which had died over night but had not bloated yet. Color not faded, I looked at the gills they were a pale( not red)I didn’t see any critters on them But I don’t really know what I am looking for).
    I added aquarium salt that directions said would treat 250 gallons and don’t really want to add more since now I am seeing sites that say not to add salt.
    What do I do here?

    Reply
    • Though low levels of salt can mitigate the harmful effects of high nitrites (which you appear to have) the fact that they are lethargic and pale gills sounds to me like low dissolved oxygen. Minimum is 5.0 but 7.0 would be better. I don’t know if you have tested that or not. The new variable here sounds like an influx of rain water so I’m not sure how that would have caused a low DO situation. In my opinion ideal levels for nitrites should not exceed 0.2 mg/l and nitrates should fall somewhere between 20-60ppm. Sometimes you will see lethargic fish with high nitrates. pH should be somewhere around 7.0 – 8.5 and you want to be cautious of rapid pH changes. So at this point if you can maintain a low level of salt, do some 20% water changes and test for DO that would be a good start.
      Hope this helps.

      Reply
  6. I have 9 Koi in a 125 gallon aquarium. One of the fish has popeye which I have been treating with Melafix for over a week now. No apparent change in the popeye, BUT the fish has started spending 10 seconds or so lying on its right side on the bottom of the tank then righting itself and swimming around. Sometimes also listing to the right while swimming. Sometimes the fish looks good others it looks like it’s about to die. I cannot see anything on or about the fish that doesn’t look right except the left popeye. the right eye seems normal.

    Any suggestions?

    Reply
    • Unfortunately pop eye isn’t associated with just one malady but in general it is from an excess of fluid or gases trapped behind the eye causing the eye to bulge. My first suggestion would be to make a quarantine tank if you don’t already have one and put your affected koi in that. Do regular 10-20 percent water changes everyday and reduce how much food you are giving that koi. In my experience, if Melafix is the solution to your problem you will see improvement relatively quickly (I’ve seen improvement overnight with melafix) so I would give it around 2 days but not much more if you don’t see improvement. If you fish is lying on its side that may be a sign of costia parasite. Costia can be dealt with by adding a little salt to y your quarantine tank. hope this helps

      Reply
      • One of my small Koi was doing the same thing. I tried all you had tried and ended up taking it to an exotic vet. After x-rays and test found it had to be bacterial and had to leave him there for injections. He is now doing very well.

        Reply
  7. i have a koi that has developed a red spot on it, its scales are raised on that area and now there are 2 new spots on its other side. do you have any idea what this is,and how i can treat it because this morning i saw another fish with a red spot just like it.

    Reply
    • Melissa, as with any health issue with koi the first order of business is to separate the affected fish into a quarantine and begin treatment to avoid any further infection spreading to the rest of the population. It sounds like your fish are suffering from some sort of ulcer typically brought about by a bacterial infection. Unfortunately it becomes a downhill slide because once a fish becomes infected and compromised that reduced health then allows for more infection and so on. So once in quarantine begin treatment with a salt bath (around 2.5 to 3.0 grams per liter). Allow the fish to be in there for a least a few days. You can also treat with an anti-bacterial as well, like Mela-Fix. Mela-fix usually works pretty quick, like around 24 to 48 hours.

      Reply
  8. Help
    We have had koi die that look perfectly well except that they lie on the bottom of the pond, struggling to get off it, within 24 hours they are dead. When a fish expert have looked at them under the microscope they can see nothing. Have you any suggestions on what we can do. The 2 koi that have died are approx. 5 months. They were small when we got them. The pond is not heated and it has no plants. The water has perfect reading and we change the water regularly.Thank you

    Reply
    • Kim, it really could be a lot of things, for example someone could have been spraying for mosquitoes in your neighborhood with some getting into your pond. Your fish could have reacted with the insecticide so you would see nothing under the microscope. Sounds like your fish are lethargic -how is your dissolved oxygen? You don’t have plants and they normally do a good job of oxygenating the pond to a certain degree. Do you have any aeration?

      Reply
  9. 3 or 4 of my Koi have developed a condition not described above. They are having large holes develop in their bodies, where their exterior and scales are eaten down to their flesh. They are still acting normal and eating. I am treating the pond with Pondcare Melafix. Can you tell what this is and if the treatment will cure them. My pond is crystal clear with huge waterfall and Safio 6500 pump. Bill

    Reply
    • Bill, from my website:
      “Ulcers on the skin of your fish result from bacterial infections that form on scales, causing them to become red. The infection causes holes, or ulcers on the exterior of the fish and will eventually result in loss of scales if left untreated. These ulcers are most often caused by poor quality of the water in the pond. Maintain a healthy, clean pond and treat ulcers with an antibacterial to prevent any further occurrences.”

      You could have something as simple as some leeches or flukes causing certain areas on the body to be exposed to bacteria already present in the pond which would make them compromised and subject to infection. I don’t know how big your pond is but if its large you may want to quarantine those affected fish and continue treatment with mela-fix and a light salt treatment and substitute your regular food for Medi-Koi. Regular 25% water changes are also a very good idea. Your pond is clear but when you’ve been testing it are you seeing any irregular readings?

      Reply
  10. I have a large beautiful Sanke. The white has started going really pink, he is swimming O.K. although mostly on top and in the air stream, also not eating, any suggestions? I have given him two salt baths for a few hrs in a large vat with air bubble, he is too big to put in the large bowl.
    I have treated the pond a month ago with Malachite and Formalin, there are no sore on him??

    Reply
    • Rosemarie, a few things on koi color. A lot of Japanese breeders will use specially formulated food to enhance the color of their koi. Additionally, water temps can have an effect on koi color-for example winter time and colder water mean brighter colors. Your koi is probably not getting food that is changing its color and its summer in the UK (which is where I think you are writing from) so most likely your koi is stressed. Being stressed can change the color of your fish and the fact that its not eating and is trying to get more dissolved oxygen probably means just that. I would check your filter, make sure its doing its job effectively. Also check your water quality and dissolved oxygen levels. Also try to check for things like organophosphates and hydrogen sulfide.

      Reply
        • Mark,
          From my site:
          “Argulus also attaches itself to fish and causes damage to tissue.
          Argulus have eight legs and rounded bodies. They also have to big
          suckers which are used to attach to the fish. Their appearance leads
          to their nickname, fish lice. These parasites can cause considerable
          irritation to fish and can lead to bacterial infections. They can be
          removed using tweezers or other small pincers. After removal, rub some
          Neosporin on the infected area. Use Dimilin or Dylox to treat the
          pond.”
          Dimilin, I believe, is now called Diflubenzuron.
          You’re going to want to treat this early as they can cause your fish
          to be compromised and thereby invite bacterial infections.

          Reply
    • From my site:
      “There are treatment options for costia. Malachite green and formalin
      can be used but you will need to make sure there is no salt in the
      pond to start with. As with flukes, potassium permanganate can be
      used to treat costia. Some practitioners will recommend a strong salt
      bath almost equivalent to that of ocean strength salt concentrations
      (around 3%). Other treatments include trypaflavine which goes by the
      trade name Acriflavine and copper. Copper is used because most
      invertebrates, like costia flagellates, have copper based blood
      (hemolymph) and therefore copper as a treatment in ponds is toxic to
      them. Acriflavine should be added to your pond at a rate of 1ml/liter
      and copper is most appropriate at 2 mg/liter. It is critical that you
      do not overdose with these two treatments.”
      Sorry for the late reply. I don’t think melafix is going to deal with
      these parasites very well. Hopefully the above paragraph will help
      with your costia issues.
      -Koi-Care

      Reply
  11. I have a collection of koi that I’ve kept for several years. During the winters I bring them indoors, which I recently did,(as my pond will freeze all the way, with, at its highest, 5-6 feet of snow on top). I noticed once I got them all in the tank that one fish has a large white patch between his eyes. there is also the same white stuff on one whisker, one nostril and one pectoral fin. It is raised and kind of fuzzy looking. the fish is otherwise overall healthy looking and acting. There is one other fish that has pop eye. My questions are what is the most effective and fastest acting treatment, can the two fish be treated together in quarantine and/or do I treat the whole tank and all the fish? this is the first problem in 5 years with these guys that I’ve had so I don’t really have a good clue what to do, and I really don’t want to lose ANY!

    Reply
    • you’re going to want to quarantine each fish: for the white fuzzy infected fish (fungus) your going to want to treat with malachite green. There is a product called ProForm C that is an effective combination of Malachite green and formalin but make sure the water is on the cooler side and well aerated. You could also do a salt bath but that won’t be quite as effective (you can go up to 1 percent salt). Keep checking on the fish as its in the bath though and the duration should be maybe 30-40 minutes.
      For the pop eye there is a medicated food called Medi-Koi that may help but pop eye is an indication that something else is wrong not necessarily a direct cause and effect of one thing in particular. Medi-Koi is kind of a catch all for fungal and bacterial issues. Most likely you are experiencing some poor water conditions in your pond that is leading to these maladies.

      Reply
  12. I have a black and white Koi. Today I noticed there is a hole the size of a dime just behind his right gill. Also, I noticed a blue line at the base of his tail. I inheritated the pond and the Koi, so I’m new to Koi.

    Reply
    • I am forwarding a previous answer from my site:
      “Ulcers on the skin of your fish result from bacterial infections that form on scales, causing them to become red. The infection causes holes, or ulcers on the exterior of the fish and will eventually result in loss of scales if left untreated. These ulcers are most often caused by poor quality of the water in the pond. Maintain a healthy, clean pond and treat ulcers with an antibacterial to prevent any further occurrences.”

      You could have something as simple as some leeches or flukes causing certain areas on the body to be exposed to bacteria already present in the pond which would make them compromised and subject to infection. I don’t know how big your pond is but if its large you may want to quarantine those affected fish and continue treatment with mela-fix and a light salt treatment and substitute your regular food for Medi-Koi. Regular 25% water changes are also a very good idea. Your pond is clear but when you’ve been testing it are you seeing any irregular readings?

      Reply
  13. I suddenly lost a 2 year old koi yesterday! the tail fins were BLOOD red. today I noticed a few more with the same. I tested the water and everything was o except chlorine which was 6.0-8.0! what should I do? thanks, Judy

    Reply
    • sorry for the late reply-well, you will definitely want to look into
      the source of your chorine and minimize that right off the bat.
      Chlorine will easily off gas if left alone especially if you have a
      vigorous aeration in your pond. If your levels are high then that
      must mean you have a constant supply of chlorinated water coming in.
      So more aeration, tablets to treat the chlorine such as sodium
      thiosulfate. Chlorine in higher conentrations is an oxidizer that can
      damage gill tissue and minimize the protective slime coat of fish
      opening them up to lots of maladies.
      hope this helps

      Reply
    • The short answer is yes, decaying plant material will definitely raise
      ammonia levels. Ammonia is essentially a nitrogenous waste and of
      course is excreted by your fish but also results from the breakdown of
      plant material via the natural decaying process. One thing you want
      to watch out for is high pH values when your ammonia is elevated
      because that’s when ammonia has a greater deleterious effect on your
      fish. I would continue water changes often (minimum of 25 percent)
      until the bacteria in your bio-filter have been able to catch up and
      handle the amount of ammonia in your system by converting it to
      nitrite.
      you may also want to get something to deal with your ammonia such as a
      detoxifier called Prime.

      Reply
  14. My white koi is in isolation for fin and tail rot and white cottony patches on his body. He seems to be responding well to Melafix, Pimafix, and pond salt, and is a little more active and his fins and tail are healing after 4 days of treatment. [Hurray!]

    I need advice because he was very weak when I started the treatment, and I would like to get him eating again. [I have some medicated food purchased specially for him.]

    This all started about a month ago… he magically appeared at feeding time after I thought the heron had eaten him along with some other fish when he disappeared two months before. When he reappeared, he had some serious tail and fin rot (all other fish were fine). I treated the whole pond with water changes and Melafix and his wounds were healing well, and he was eating and behaving normally. But when I came back from an 8 day business trip, I found him floating at the surface on his side under a water lily leaf (which is why my friend tending my pond didn’t see him.) {heavy sigh}

    So now he is in treatment in isolation he is improving daily, but I am worried about how thin he is and long it has been since he has eaten. So my questions are:

    How long can a sick koi go without food before it affects their health? I read that I am not supposed to feed during treatment, but is it a good idea to suspend treatment and try to get him to eat while in isolation? Or should I give him a vacation in the pond to see if he will eat? I am afraid he will just hide again — he is apparently great at hiding under the ledges, pots, and other places.

    Thank you for an advice you can offer. This is the first time I have had to treat a sick koi, and I really want to get him to a full recovery.

    Reply
    • Sounds like you’re taking all the right steps to bring your koi back from the
      brink. You’ll read a lot about not feeding your koi during quarantine
      etc. and for the most part that’s good advice but at some point a lack
      of food and nutrition could cause a sort of downhill slide. Lack of
      nutrition for extended periods will make it more difficult to get your fish
      back easily and that time frame will depend on the size of the fish,
      water temperature etc. I would say if you are seeing real improvement
      and its in quarantine then I would try something like Medi-Koi and if
      it doesn’t eat ( or eats little) then simply pull out the uneaten
      food. You could even do something like pineapple or peas or other
      fresh vegs and fruits.

      Reply
  15. I have used Melafix on my pond to prepare for the long winter.
    One of the koi had started to float sideways. I went to the pet store and they told me to add charcoal to remove the medicine and do a water change. The koi is still floating sideways and I don’t know what else to do. i tested the water, it is fine.

    The pet store said the melafix makes the fish gill stick and it is hard for them to open it.

    Any solutions

    Reply
    • I’ve never heard of Melafix having that effect on the gills of koi.
      I’ve always had a very good experience with it. Floating sideways
      sounds like it could be bacterial but realistically could be parasitic
      in nature as well. Unfortunately there is a lot that can go wrong with
      koi but you may want to try something like Medi-Koi if you don’t want
      to treat with Melafix.

      Reply
  16. I brought my fish indoors for the winter. They are staying in 100 gallon tanks. One tank is doing well, while the other has fish gasping at the surface next to bubblers and also by the filter. I have 4 bubblers and two filters pouring into the tank…..How could it possibly be a lack of oxygen? Lost my first fish today. Some are eating, while some are not.

    Reply
    • (Koi-Care Staff):
      it probably isn’t the aeration. When you tested the water of each
      tank how does it look? Sounds like something(s) is off with respect
      to water chemistry in one tank.

      (Reader response):
      Thanks for the response regarding my koi issues. Upon doing more research, it seems that it may be a nitrate issue. A salting is suggested and that is the course of action which I’m trying. They are no longer gasping for oxygen at the surface bubblers or filters. They are swimming much more normally. Daily small percentage water change, too. Hopefully, this does the trick.

      Reply
  17. I resently had a badamonia spike, lost several fish. Took out fish and drained pond, cleanedpond compleatly. Even power washed liner and rocks ect. Everything seened fine for a few months, then noticed blood streaks in one butterfly koi, now another has blood spots all over . Butterfly koi seems to be flicking and irritated. Been koi keeping for Many years with very little problems, don’t know what to do.

    Reply
    • I’m not sure where you are located but if you were in a region where
      you experience seasonal changes and have trees nearby your pond you
      may be getting falling leaves into your pond. The decaying leaves in
      your pond have the capability to then raise your ammonia levels.
      Additionally, your bio-filter may be insufficient for whatever reason
      and need to be “re-booted” as it were with a fresh crop of nitrifying
      bacteria. Aquatic plants are always a good idea because they tend to
      assimilate nitrogenous waste well (ex. water hyacinth). Obviously
      water changes are going to be in order until ammonia levels start to
      fall but using an ammonia detoxifier such as Prime may be a good idea
      as well. I’m not sure what is causing the spike, especially after you
      cleaned your pond out so thoroughly but the fact that it keeps
      happening suggests to me that your main problem may lie within the
      bio-filter. Also, how is your aeration? A more vigorous aeration can
      also help speed along the process of getting ammonia out of the
      system.

      Reply
  18. Thank You for all this information, it has helped me considerably. I only have one problem I cant figure out. I change my water and clean the filters once a month except at this time of year as it really isn’t needed. I have a mixed pond with mostly Koi and 2 Goldfish. One of my goldfish seems to have a large white “wart” looking protrusion on the side of it’s stomach. I’ve tried many different types of medications, such as Melafix, Parasite control, etc… I keep my PH in track with oyster shells and various additives if needed. I do have Carbon Powder i have no idea how to use. I have inherited this pond and learned to love it and learned on my own by posts just like these.

    For some reason I can’t find a solution to this guys problem. I also have severe bloating on the other Goldfish. Can these problems spread to my Koi as some are 15+ yrs old.

    Reply
    • If your goldfish with the bloating is otherwise fine and still eating ok then that kind of thing is not entirely unheard of and may not adversely affect that fish (it doesn’t sound like a swim bladder disorder). If its bloated and and the scales are kind of raised then it would be something like dropsy. Your fish with the protrusion it sounds like a fungus of some description.
      This is from my site:
      Some causes of fish infections, such as fungal hyphae or spores, require a microscope to see them. Mild or moderate infections can be treated and possibly cured if they are caught early. These types of fungal infections are not typically contagious and usually only a single Koi becomes infected.

      Treating Fungus: Fungus can be removed by gently rubbing the area with a cotton swab while the infected area must be treated with an antibiotic or antimicrobial cream immediately afterwards.

      Fungal infections in fish almost always begin externally and start through a break in the outer skin layer of the fish. Affected Koi usually display fluffy or cotton-like growths on their skin. These growths may also exhibit a green tinge because of algae growth on the fungus. There may also be raised white, brown, yellow or green irregular bumps seen on the fish’s fins. Most infections can be successfully treated if caught early so it is important to visually inspect your fish frequently.

      I would definitely quarantine this fish if you have the facilities to do so and treat it by hand with an antibiotic cream like propolis after you have treated with a fungicide like malachite green. Both applications can be done with a cotton swab.

      Bryce, not familiar with carbon powder but if i had to guess it sounds like a derivation of activated charcoal whose function would be to reduce excess nutrients in your water and keep things like excessive algal growth to a minimum. If you anesthetize your fish first then use to the cotton swab to physically remove the fungal growth (if that is what it is) as well as treating it with malachite green- that is the objective. Then you will want to treat with some sort of antibiotic cream. Don’t worry about things washing off-that cream should lock it in. You don’t want your fish out of water for too long just like a person doesn’t want to be underwater for too long.

      Reply
    • Often times when winter rolls around and water temperatures drop one many experience some instances of carp pox which are raised bump-like structures on the fish’s body. Unfortunately there isn’t a treatment for it but it isn’t likely to kill your fish either. Carp pox will typically go away when the water warms up again. Another round, raised structure that could be on your koi is the argulus parasite but they are typically greenish in color so carp pox seems more likely in this case. Either way you can always add a little salt to your pond to make it easier on your koi- bring it up to about 4 or 5 parts per thousand.

      Reply
  19. One of my pretty large koi has developed big/ bulging growth on two parts of the back. I separated it for almost five days and treated with Melafix and then rock salt for five days. No change – but now these pusy looking bulges are growing. I have consulted local pet stores, performed water changes etc. What else can I do? Am I going to lose this koi?

    Reply
    • From my site about raised bumps.
      “Fungal infections in fish almost always begin externally and start through a break in the outer skin layer of the fish. Affected Koi usually display fluffy or cotton-like growths on their skin. These growths may also exhibit a green tinge because of algae growth on the fungus. There may also be raised white, brown, yellow or green irregular bumps seen on the fish’s fins. Most infections can be successfully treated if caught early so it is important to visually inspect your fish frequently.
      Treating Fungus: Fungus can be removed by gently rubbing the area with a cotton swab while the infected area must be treated with an antibiotic or antimicrobial cream immediately afterwards.”

      So a fungal infection is one possibility. The other possibility is Costia-see below.

      “Costia, like Flukes, are a parasite. In this case it is a microscopic flagellate that can reproduce rapidly. Typically koi don’t suffer from costia unless they are already compromised in some way to begin with so it would be classified as a secondary illness. Your koi will appear lethargic and will attempt to flash or rub on the sides or bottom of the pond to itch and rid themselves of the parasite. The skin will also appear whitish/grayish on the infected are of the koi’s body. Though these parasites can affect the skin they will also infect the gills of your koi as well.

      Treatment: There are treatment options for costia. Malachite green and formalin can be used but you will need to make sure there is no salt in the pond to start with. As with flukes, potassium permanganate can be used to treat costia. Some practitioners will recommend a strong salt bath almost equivalent to that of ocean strength salt concentrations (around 3%). Other treatments include trypaflavine which goes by the trade name Acriflavine and copper. Copper is used because most invertebrates, like costia flagellates, have copper based blood (hemolymph) and therefore copper as a treatment in ponds is toxic to them. Acriflavine should be added to your pond at a rate of 1ml/liter and copper is most appropriate at 2 mg/liter. It is critical that you do not overdose with these two treatments.”

      Costia usually takes the form of small red bumps, not sure how large or what color your koi’s bumps are presently. Having not seen it I would lean towards a fungal infection. Sorry I can’t be more help

      Reply
  20. I noticed last week that one of my fish had disappeared. I suspected a raccoon. However today I noticed a fish swimming a little funny. Kind of off to the side with a twist. There are 8 fish in an outdoor pond. The rest seem find and they are breeding so I figure they are pretty happy. Dont do much to the pond water but filter an airate. If I add water I declorinat. They have all seemed pretty content for years. First sugn of and issue. What could this problem be?

    Reply
    • Your fish could certainly have had a run in with a raccoon-the animal could have injured your fish in an attempt to snag it from the water and now your fish is swimming irregularly because of it. If your water quality doesn’t show anything unusual then it may just be something like what I suggested above that is affecting only one of your fish. It may be a wait and see kind of thing.

      Reply
  21. I have some black koi, several have a white smooth patches on head & body. Looks like scabs. Several have had these for several years No problems swimming or eating Pond people who clean my pond every year said to use salt treatments but that did nothing Do you have any idea what it is and how to get rid of it? Thank you

    Reply
    • Pat, this sounds most likely like Carp Pox which is a herpes virus. This is pretty common among these fish and really shouldn’t be a health issue to your fish unless their growth causes them to have trouble feeding (by growing in or around their mouth). There’s no real treatment for carp pox but typically raising the water to above 60 degrees will help regress the virus a bit. Carp Pox is usually something that becomes more pronounced during that seasonal shift to winter as dropping water temps tend to spark the herpes virus activity and growth.

      Reply
  22. Thanks for answering my question cause no one else had any ideas what it is. One more question about carp pox, will it spread to my other fish? One again thank you so much.

    Reply
    • Yes, it can spread so if you really don’t want others afflicted you may want to quarantine or cull those fish with the pox. As I said before though, its not the worst thing koi can have and they can live fine with it. Young koi juveniles are actually more susceptible to it and can suffer mortality because of it.

      Reply
  23. We have an outdoor pond that contained three adult koi and around twenty baby fish. Most of the babies have died and our two biggest fish have also. We have checked the water multiple times and it seems fine but when the fish die they have white cotton-like substance on them. They were found by our water fall and we do not know if that is caused by a disease or if the white substance is just the fish decomposing. We could really use help to save the remainder of our fish.

    Reply
    • It sounds possibly like it may be fungal in nature. This an excerpt is from my site:

      Fungal infections in fish almost always begin externally and start through a break in the outer skin layer of the fish. Affected Koi usually display fluffy or cotton-like growths on their skin. These growths may also exhibit a green tinge because of algae growth on the fungus. There may also be raised white, brown, yellow or green irregular bumps seen on the fish’s fins. Most infections can be successfully treated if caught early so it is important to visually inspect your fish frequently.

      Melafix and an addition of some salt to your pond may be in order. How do your other fish look?

      Reply
      • What type of salt would I use and how much for a 20 gallon aquarium? I am using melafix at a rate of 2 teaspoons per day for 7 days to treat a couple Koi for mouth not opening.

        Reply
        • I have a salt calculator on my site but the amount will depend on what percentage you are trying to achieve. Are you looking to just provide some osmotic relief or trying to combat a disease of some sort? Whatever you add you will want to do it over several days.
          -grant

          Reply
  24. I have a mixed breed small pond in my backyard koi, black moor, fan tail, a channel catfish, and tadpoles. Recently my black moor developed one white spot just behind the gill but behaves normal as do the other fish. This spot is about 2mm in diameter. Im unable to diagnose the problem myself and would greatly appreciate any help. I love my fish and would hate to lose any. I do live in Colorado so my water temperature is low and I have not fed my fish as a result if that helps. Please advise on possible causes and treatment thank you.

    Reply
    • It sounds fungal to me. This is an excerpt from my site regarding fungus.

      “Fungus can be removed by gently rubbing the area with a cotton swab while the infected area must be treated with an antibiotic or antimicrobial cream immediately afterwards.”

      White spots could be several things though such as Trichodina which is a parasite as is White Spot. Cotton Wool disease is another ailment that causes white on the body -its fungal in nature. I would quarantine this fish and do the treatment described above. You can also treat fungus using something containing malachite green like Proform C.

      Reply
  25. one of my koi fish that is a male,looks like it is full of eggs,he is blown up and struggle to come up for food,please help

    Reply
    • there are a few possibilities going on here. 1) you may be overfeeding your koi and therefore your bloated koi simply has excess weight gain. 2) you have an excess of harmful bacteria in your water and your bloated koi has internal bacterial infection that is causing the bloating. 3) the koi you think is a male is actually a female and full of eggs. If you are feeding like 3 times a day I would reduce that for sure. Otherwise I would check your water chemistry and make sure your levels aren’t off

      Reply
  26. I just took a close look at my koi since the harsh winter and noticed that one of the butterfly koi has some kind of growth coming out of his mouth. Kind of looks like a bubble of tissue. Looks fine otherwise . Any ideas? They haven’t begun eating yet for the spring. Thanks.

    Reply
    • What you’re describing sounds like it could be mouth rot. Below is an excerpt from my site regarding the subject:

      Mouth rot is a symptom of something larger and that is usually poor water quality that is causing your fish’s health to be compromised and open to infection. You’re going to want to stop feeding for the time being and start improving your water quality by doing a 30% water change. Next thing would be a light salt bath treatment and perhaps a treatment of Mela-Fix. You will also want to monitor your water quality by testing it regularly. You can also remove the fish and treat the sores with hydrogen peroxide or iodine.

      Reply
  27. several of my 40 koi which were all born in this 2,000gal pond a few years ago have developed blister like structures on the heads and bodies…one last summer had such a grotesque flowery growth on its head that my granddaughter nicknamed it flower…these growths do continue to grow in size…all are acting normal..as I took the one with the large flower out of the pond by net, the blisters easily ruptured while in the net…no ulcer was noticed where the growth was…I would appreciate some advice …thanks

    Reply
    • My best guess here would be carp pox. Because your fish are doing well otherwise and carp pox usually shows up when there is a drop in pond temps (fall) or a rise in pond temps (spring) I would be confident is saying that is what it is. Its a herpes virus and there is no cure -your fish will always have it to some degree but it should lessen as you get into summer and temps are more steady and high. I don’t recommend cutting them off as this may spread the virus and open the fish to lesions and infection.
      good luck , Koi-Care

      Reply
  28. Hi I have a white koi carp about a year old and I gone out today to feed them and this one fish is upside down in bottom of pond still alive it nt eating and all it’s belly has gone a pinky red colour am not sure on what to do or if it’s ill any help would be great full thank you

    Reply
    • the first thing you should consider is getting this fish in a quarantine tank and adding a bit of salt. Salt will help in a couple different ways including making conditions more difficult for some viruses and bacteria to do well in and making it osmotically easier on the fish. You will also want to feed you fish some frozen peas. It appears that your fish may have a swim bladder disorder and it may be caused by a virus or bacteria -its tough to say for sure with swim bladder issues. Make sure the quarantine tank is sufficiently aerated.
      hope this helps, Koi-Care

      Reply
    • this is a bacterial induced disease called dropsy and is associated with spring and rising water temperatures. One treatment you can put into play is injection of antibiotics and putting the fish in quarantine. There is most likely severe kidney damage already so there isn’t a great chance of survival at this stage.

      Reply
  29. I have a koi that is bent. It looks like it just stays in one spot but it doesn’t. I don’t think it can swim normally but it doesn’t move when I try to get it to move. I tried to hand feed it but it only took one stick then wouldn’t open it’s mouth again. Do you know how to help me? Thank you.

    Reply
    • It is difficult to assess without seeing it in person but I’m assuming that this bent appearance began recently (i.e. it hasn’t been this way since it was a fry). So if this is a newer thing then there are a few explanations possible; 1) electrical leak in your pond from something a submerged pump 2) air bladder problems 3) internal tumor 4) vitamin C (ascorbic acid) deficiency causing scoliosis and/or low quality food causing scoliosis. Electrical leak is unlikely but the others are all possible though I would put my money on the Vitamin C deficiency and if that is the case you can reverse it over time by increasing the Vit. C in this fish’s diet. Sorry I can’t be more help.

      Reply
  30. Hi, I have a 6500 gallon koi pond. Three days ago I noticed my biggest koi was resting on the bottom and not eating. She was fine and eating the day before. We had a blue heron hanging around so I thought she was scared. We were told to add a little salt to decrease her stress. Well yesterday, we noticed her gills were a little swollen and the sides of her face discolored. We brought the salt up another 0.1%. We did that again today. It is now up to 0.3%. I was suspecting some sort of gill parasite. Today, after we added the salt, she seems to be swimming around more. I know that she is probably irritated by what is going on and the salt. I will I know if this is working. Is her swimming around showing she is getting better?? I was told to continue and increase the salt to 0.6 to make sure the parasite or bacteria is killed. Is that true?? I really do not want to lose this fish!!

    Reply
    • 0.5 to 0.6 is acceptable and should take care of gill flukes if that is the case with your fish. Salt additions to your pond act as an osmotic relief to fish and will result in more slime coat which is a koi’s first line of defense, so to speak. Just remember that you don’t want to keep your pond salty year round as you may end up with parasites that, over generations, will become more salt tolerant. yes, if you fish is starting to swim around more then it is undoubtedly doing better. You can also try feeding your koi “Medi-Koi” as a precaution as well. The other thing to keep in mind is that to bring your salinity back down you will need to do water changes because salt won’t evaporate (sounds obvious but many people don’t think of that).

      Reply
  31. I have a koi with thin appearance. It looks like it just stays bottom of the tank and difficult to breath. Sometimes it tries to swim then falling sideways & looks so stressful. Not eating for few days.I want to save my Koi.

    Please help!

    Reply
    • As with many illnesses that can’t be diagnosed right away its always a good idea to quarantine your fish in a separate place, add a little salt to the water and some melafix. It could be that your fish is suffering from something stress related like harassment from other fish or perhaps it has a bacterial infection internally or externally somewhere. If its having trouble respiring then you may have high ammonia levels in your tank which would cause a cascade of health problems with your fish. So after you quarantine I would check water chemistry in your pond -most often your fish’s health problems will stem from there.

      Reply
  32. Hi koi Care,
    Thank you for your prompt response. This fish is not eating any food for more than a week. Any suggestion for a vitamin or liquid food I can dissolve in the water. This fish is approximately 8cm long.

    Thanks!!!

    Reply
    • well if its internal and bacterial in nature then salt and melafix will help. if you can get the fish to eat try Medi-koi. Otherwise you may have to do antibacterial injections. You could actually try koi clay to add to the water since koi love it so much but honestly I don’t know if that will help.
      sorry i can’t be of more assistance

      Reply
  33. We have a 12 – 14″ koi that has developed what looks like a tumor on it’s left side behind it’s gill. We have had this fish for several years in an outdoor pond (Long Island, NY) with about 8 other fish (koi & goldfish). It seems to be very fast growing, noticed it yesterday & it is much bigger today. Other than this growth, the fish appears to be fine, eating & swimming normally. What could this be & should we separate it from the other fish?

    Reply
    • Tumors can be malignant or benign so you may be able to leave this fish as is without any further problems however if its malignant or grows big enough to hinder the fish then that is when you will want to consider having it removed. If you have it removed that is when you will want to quarantine the fish and treat the water with something like melafix so that there aren’t subsequent infections at the surgery site post removal.

      Reply
  34. Hey,I have 15 koi fish now,I don’t know it is from where and I bought few yesterday…however I go near them,I found them not so hyper and kept their self under it.only when I feed they will come out??can I know why???and I had a koi fish almost 6 month I rare it,after I mixed them with the fish,the 6 month year koi doesn’t active and look dead,,I rare them in aquarium..quick big and those koi are still small,not so big but maybe around our middle finger length,can I know why happened??and what is the treatment???if u put those general aid chlorine into it,6-7 drop,will they die as well or can’t take it??

    Reply
    • They may be scared to come out because there may be a bird or another animal that is trying to eat them when you are not around so they are scared to come out.

      Reply
  35. I have a golden koi which appears to have white wisps behind its gills. It is active and feeding well but from time to time it lies at the top of the pond on its side.I have isolated it and used pond salt and mela-fix. Can anyone advise?

    Reply
    • the following is from my website:

      Anchor worm, also known as Lernea is a crustacean parasite that attaches to, and digs into the skin of fish. The female Lernea attaches to fish while males do not. The worm feeds on the fish, damaging its tissue. This leads to a bacterial and/or fungal infection on the fish. Another crustacean parasite, Argulus also attaches itself to fish and causes damage to tissue. Argulus have eight legs and rounded bodies. They also have to big suckers which are used to attach to the fish. Their appearance leads to their nickname, fish lice. These parasites can cause considerable irritation to fish and can lead to bacterial infections.

      Treating Anchor Worm: They can be removed using tweezers or other small pincers. After removal, rub some Neosporin on the infected area. Use Dimilin or Dylox to treat the pond.

      From your description it sounds like Anchor worm.

      good luck

      Reply
  36. Hi everyone.
    Have a question that no one, including “dr. Google”, can answer.
    I have a fantail about 12-14 inches long who suddenly began to segregate herself from the rest of the gang in the 6,000 gal. pond.
    I watched her a couple of days and saw that she couldn’t reach the surface with out EXTREME struggle. She was never laying over.
    I set up a QT, (150 g.), and have been cleaning it daily.
    Here’s the question.. when I caught her and really checked her over there was nothing in her mouth, or gills, no signs of any parasites at all, no sign of disease, BUT her spine is SEVERLY curved?? She has never been that way and none of the others are either.
    I had checked for injury, nothing obvious.
    I am ASSUMING its scoliosis. I have been heating, cleaning, salting, aerating and feeding her medikoi. I also decided to add powdered pure Vit. C to her water.
    I realize that could crash the PH but have checked it…all ok.
    Has scoliosis ever been reversed? She has been pooping up a storm, so she is eating. I am considering putting her back in with everyone else but watching the poor thing struggle to get to the surface to eat and having no coordination to do so is cruel.
    Does ANYBODY have any ideas to try, or is scoliosis irreversible!
    THANK YOU, THANK YOU, THANK YOU!!!

    Reply
    • So if this is a newer thing then there are a few explanations possible; 1) electrical leak in your pond from something like a submerged pump 2) air bladder issues 3) internal tumor 4) vitamin C (ascorbic acid) deficiency causing scoliosis and/or low quality food causing scoliosis. Electrical leak is unlikely but the others are all possible though I would put my money on the Vitamin C deficiency and if that is the case you can reverse it over time by increasing the Vit. C in this fish’s diet (I don’t think adding it to the water will be as effective as feeding the fish something with vit. C added). If you need to get a certain food to your fish on the bottom you can always attach it to a rock or something heavy. So for example you could attach a yellow bell pepper to a rock with cordage or zip tie or something similar and send it to the bottom. Another veg. High in ascorbic acid is kale and that can easily be delivered to the bottom.
      Sorry I can’t be more help.
      -Grant

      Reply
  37. Dear Sir,

    I have written once before, but I have further observations that may give you a further clue as what the disease my koi carp carries.

    There seems to be a mucus covering most of the body which has made identification a problem. There is no sign of an injury or of the fish scratching itself, although the scales do seem slightly raised. There is yet no sign of pop eyes, but I have noticed thick white lumps on the tail of differing sizes ( NO FIN/TAIL ROT ). It’s fins are kept in, causing a slight abnormality to the normal swimming pattern. The body is slightly thin and it stays close to a water fall, presumably for oxygen. When it is not by the fall it stays at the top but is not gulping for air as expected. I have not observed if its feeding properly except I must say I haven’t seen it feed. There are two other koi in the pond which so far do not seem affected.

    I hope this helps.

    Regards

    C R C Burman

    Reply
    • Cyril, this is an excerpt from my site:

      Your Koi fish may have Lymphocystis, also known as Carp Pox if it has any buff discoloration on its skin. Another sign of Lymphocystis is shiny, greasy looking skin. This condition occurs when the water temperature in the fish’s environment has changed. Lymphocystis and Epistylis look alike, but they each respond differently when salt is added to the fish’s environment. Carefully watch the fish for a week after adding salt. If you still notice the symptoms mentioned above, then the fish is suffering from Epistylis. Epistylis is an uncommon parasitic infection that is dangerous and can cause other diseases and ulcers in your Koi. It is usually caused by poor management of the water, resulting in dirty water infected with parasites. If you do not regularly change the water in the pond, it can easily become a host to these parasites. Epistylis looks like a fungus and thrives in ulcers and wounds on Koi fish. You can identify an infected fish if you see white colored tufts in and around ulcers and wounds on the fish’s skin. Change the water in the pond and add salt to combat these parasites.

      If its epistylis you can also treat with formalin-based solutions.
      Carp pox has been known about in the koi world for over 400 years so its definitely not new but unfortunately this herpes virus is chronic though not necessarily life threatening. Clamped fins is typically a result of stress. Raising the water to over 60 degress F will help if its carp pox. Viral afflictions can be difficult to diagnose as a general rule, a lot of the symptoms are similar.

      Reply
  38. I have lost 2 KOI and a third one is showing the same symptoms, They developed a red spot on their bodies in the same place, right side of body right below the dorsal fin. I tested the water, PH=6.5, ammonia=0.25, nitrite=0 and phosphate = 10. I was told these reading were OK yet my fish are still dying. I am a novice at owning KOI, they came with my house when I bought it. Any help and suggestions would be appreciated.

    Reply
    • Hi Jeff, sorry for the delayed response. You could get away with at pH of 6.5 but between 6.8 and 8.2 would be better. Remember that the pH scale is logarithmic so any small swings are a big deal. Ammonia really should be zero and your nitrite looks good. It sounds like your koi may be experiencing ulcers on their bodies and ulcers are typically a sign that something larger is going on. Ulcers are often caused by parasites that get on the skin and through invasive parasitic action expose the area to bacterial infection and ulcers. What you can do is feed with Medi-Koi and try to treat the external bacterial infection with Mela-Fix.

      Reply
  39. 15 plus year old large Koi, one of about 8 but the only obviously sick one. has lost a lot of weigh/size and body is now bent, curved, appears to be very sick or dying?

    Reply
    • Sounds to me like your fish has some degree of scoliosis which is most likely due to a lack a vitamin C in its diet. Try attaching something high in vit. c like kale or green bell peppers to a weight and put it in the pond. You could also quarantine the fish and feed the same -that way you could be sure the afflicted fish is eating.
      -grant

      Reply
  40. I have a Koi that’s suddenly floating on the surface, its tail is swollen and almost pineconing but not all over the body, with what looks like a slight mucus, and it is keeping the fish from swimming properly, its rectum seems also very large and swollen out, PLEASE HELP!

    Reply
    • that sounds like an internal infection of some decription. You need to quarantine this fish and feed with medi-koi or something similar & add a little mela-fix (in the event that you also have external infection) to the water as well as some salt. You may need to do anti-bacterial injections as well but you will need to call someone in to do that.
      -Grant

      Reply
  41. Hi. I have two mature (6 years old) laying on their sides at bottom of pond. But they do still swim normally around most of the time. It is winter in South Africa. Please advice.

    Reply
    • could be a lot of explanations for this behavior. What kind of water temps are you seeing? how are they eating? is your water chemistry in good shape?

      Reply
  42. Hello,

    I have notice today that one of my largest black carps has developed white fluffy, cotton wool like spots all over his body. He also looks like he is gulping for air sometimes. I cleaned the entire pond water out a few months ago and regularly was the filter foam out. What can I do to treat him?

    Reply
    • Definitely sounds like columnaris or cotton wool disease. You can treat the water with potassium permanganate. The gulping for air sounds like the fungus has made its way to the gills hence the labored respiration. You can remove the fungus on the body with cotton swabs and an antibiotic cream to follow. You may also want to consider antibiotic injections for the fish as well.
      -grant

      Reply
      • Thanks for the reply. Before your response I went to my local pet store and I bought Blagdon Anti Fungus and Bacteria treatment. It’s a combination of Acriflavine Hydrochloride and Malchite Green Oxalate. It’s a five day course and the cotton wool like growths have definitely reduced so far.

        The back of the packaging says this product is safe for wildlife using the pond, I suppose including my dog! I’ve read that MG is a carcinogenic, does this apply to the oxalate variety too? My dog likes to drink out of the pond and I’m not sure how long after treatment it is safe for him to drink from it again. Do you know much about this sort of product?

        Reply
  43. We moved into a house with a very small pond (maybe 2-3 feet across by 3-4 feet wide and a few feet deep) a couple months ago. It has 4 smaller Koi (about 5-6″ long). Came home today and two were dead, the other two look like they’re in bad shape. They will get close to the surface and look like they’re almost gasping. Any idea how to save the two??? I feel terrible. I know there is an algae problem. There is a pump. The previous owner left some algae cleaning stuff that says it’s safe for fish. We’ve used on occasion, but not too much. Now I’m afraid I poisoned the fish. Can they be saved? Do I try to take them out of the pond in a bucket or something? If so, what temperature of water? It’s been in the high 90s outside.

    Reply
    • You didn’t poison the fish but they appear to be swimming in water with poor chemistry. If you have bad algae you most likely have excessive ammonia and/or nitrites. This will essentially burn the gills of your fish and cause them to gasp. Antother thing is that you may not have adequate aeration and this is especially a problem in a small pond with high temps. Hot water doesn’t hold as much dissolved oxygen so you need to make sure you have air stones or something similar. you can certainly try to save the remainder by putting them in quarantine and dealing with the water quality of the main pond.

      Reply
  44. I have a 2400 gallon pond with 15 Koi (1) 16″ (1) 12″and the rest 4-6″
    A couple of weeks ago I noticed the largest Koi has reddish / pink on the tail and then some ulcers on the tail. I did a some homework and assumed it was tail rot and started treating the whole pond with Melafix. After a treatments of 12 oz. for a week it appeared the reddish pink improved but the ulcers were still on the tail. I increased the Melafix to 16 oz. for another week and with no improvement.I also got the salt level up to .1 I now have the Koi in a separate tank with aeration only, no filtration.I am now using Melafix and Pimafix and am utilizing pond the pond water and doing a 50% water change daily just before dosing with the Melafix and Pima fix. The koi is eating and was eating like a pig when he was in the pond. I think I was over feeding the pond and this is what possibly caused the problem. All the other fish seem fine and active. The pump is moving about 4500 gph. The water appears to be good with minimal algae,(enough for the fish to eat) 25%water Lilly coverage. I do need to get a water sample to a local pond shop for analysis. Thanks so very much for your help, I am desperate. Not only to I want to cure the Koi but want to figure out what is the possible problem in the Pond that had been so perfect and almost maintenance free for years.
    Thanks Curt

    Reply
    • The melafix is a good plan as are water changes but I would definitely quarantine your fish -its so much easier to treat and you can be sure that it is eating any special foods that you give like Medi Koi (which you may want to look into starting). You may have high ammonia but the signs are typically fish gasping at the surface and clamped fins. You may have some water quality issues though that are allowing for the bacteria to cause the observed fin damage so I would consider a boost to your filter media by adding something like “Microbe Lift” -this will supercharge your beneficial bacteria loads and help remove excess nutrients in your pond that result from overfeeding etc. Also, you can bring the salt up to 0.5 to 0.6 -there is a theory that over the time and generations of bacteria, they have become less affected by salt and therefore higher levels are needed to kill them. Just remember that if you do whole pond treatement that salt doesn’t go away unless you do water changes following treatment. Ideally, if you do a quarantine with higher salt, melafix and medi koi and do a whole pond treatment with microbe lift you should be in good shape.
      Hope this helps, Grant

      Reply
    • Roberta,
      You need to quarantine your fish, first off. Then increase the salt concentration to 0.5%. You will want to treat the water with mela-fix. Make sure your quarantine has good aeration and filtration. Your pond water probably has an increase in excess nutrients that allow bacteria, like the one most likely causing the red spots, to thrive. You will want to test your pond water on a regular basis and watch for ammonia, nitrites, nitrates. You can even do something like microbe-lift to boost your beneficial bacteria load in your filter media.
      Good luck, Grant

      Reply
      • Thank you so much for your reply, Grant.
        I have a 2500 gallon size pond. So far, one of the local fish guy came and added #5 of salt then some blue liquid…..Proforma C? It has been about 6 weeks and the poor fish still has the red spots (none of the other 5 has the problem). However, it eats and swims around normally. I have been keeping up the level of water and cleaning the filter system where at least 10-20% fresh water is added.
        Should I dump some Tetra Pond Fish Treatment in or more salt or ? There is no way I can quarantine that fish.
        Thank you Grant.
        Roberta

        Reply
  45. My Koi keep spinning in the pond…I quarantine her and add salt, green and blue medi and heater to 30 deg with oxygen… but seems like nothing much better… She still keep spinning.

    Reply
    • My best guess would be parasites -they are perhaps bothered by them and/or trying to scrape them off. You may also want to check your water chemistry to see if anything is out of line.

      Reply
  46. i hav som small coi fishes in an aquariam in my living room.when i buy them they stay alive for about 1 week and then they start dying out.they start to swim upside down then swim with extra speed then start hittin on the aquariam.then they die cud someone please help me out here.

    Reply
    • Sounds like your water chemistry is bad. You may have an excess of ammonia. Start with the water chemistry -test it or have it tested. Make sure your filter is appropriate for the size tank you have and that it has plenty of beneficial bacteria on it.

      Reply
  47. I understand that this isn’t Koi related, however I am at a loss. I have a Black Moor Goldfish who I just treated for Ick last night. As of now, it has completely gone away; however I am now seeing a strange lump sort of greenish yellow in color on his gill flap. He had no injury or stressful situation…. does anyone have an idea?

    Reply
    • that sounds like a parasite. Is it irregular in shape or like a round, humped disc? the Ich may have compromised the fish enough to allow a parasite to take hold.

      Reply
  48. I have a butterfly ongon. It has pinkish blobs on it which I think is koi pox but at the same time the fins are all shredded. None of the other fish are affected. I am currently treating them all with anti bacterial food. Do you have any other suggestions? I thought maybe fin rot but there are no red streaks.

    Thanks Crystal

    Reply
    • A few possibilites:
      1) high ammonia or nitrites
      2) stress induced fin fraying
      3) dietary deficiency
      4) Pseudomonas Bacteria
      check your water chemistry and do water changes if necessary. be sure you have plenty of aeration. medicated food that your are feeding won’t hurt. Koi pox you can’t do much about unfortunately. Once you test the water that will help you determine the appropriate next step. If your water chemistry is good you may want to quarantine the affected fish though so you can better administer treatment.
      -Grant

      Reply
  49. I have 10 butterfly koi in a small pond, approx 1700/2000 gallon of water. One koi recently started sort of laying on the bottom but he would swim with the other fish then go back to the bottom and just lay. Today I saw he has like grayish fuzzy stuff on him. I put him in a net by himself and am going to put him in something with oxygen until I figure out what is going on. One other fish sort of looks like it has jagged fins. Any suggestions on what may be going on and how I can fix this? Thanks?

    Reply
    • First off, test the water chemistry and look for high nutrients like ammonia and nitrites. It sounds like your fish with fuzzies could have either fungal hypahe or ich-both are on the common side when it comes to fish diseases. For fungal issues consider a product like “Pimafix”. Its a product made from the extract of the West Indian Bay Tree which has natural anti fungal properties. Another product with a similar name, Melafix, is extracted from the maleleuca tree and has antibacterial properties. If the fuzzy stuff is ich there are a couple of treatments that I list in my diseases article( http://koi-care.com/koi-diseases-treatments/). As far as the tattered fins go ,that may be a sign of dietary deficiency but more likely its a sign of stress ( potentially stress brought on by high ammonia. That’s the reason why checking water chemistry should be first on the list as poor water quality can make your fish vulnerable to other nasties that may be in the water.
      -grant

      Reply
  50. I had one koi lay on its side gasping for air I took it out and it died quickly then one of my older kio did the same this fish is approx. 1.5 years old which is about the same age as my pond I took this fish out putting in a separate tank and then added aireation and baking soda I had installed a new type of medium in my bio tank and I am sure that this had some type of reation and sickened my fish I did a 30% water change and my other 10 or so fish are lathargic and not eating now what should I do?

    Reply
    • yeah, sounds like whatever happened can be traced to the medium. Almost sounds as if they were poisoned. I would suggest getting rid of that medium and going back to what you had before. Keep doing water changes regularly but watch for pH spikes. Have the water tested and look for something that may have caused your koi to have a hard time respiring like burned gills from high ammonia.

      Reply
  51. I brought a grade a koi carp and a blue film has appeared over his eye and scales on one side, he also seems a bit limp at times and has trouble using his fins, any idea what this could be? And if it will spread to my other fish.

    Reply
    • Kira,
      those symptoms can be attributed to several things but the most likely it is that water conditions are off balance and therefore supporting bacteria in your water and thereby causing a film over your fish’s eye (“Cloudy Eye”) and scales. It can afflict your other fish. In addition to adding salt to your pond try this as well (an excerpt from my site):

      Cloudy eye is somewhat uncommon but it can occur. This malady is typically a symptom of something else going on rather than something attacking the eye specifically. Some causes are bacterial infection, a cataract or even lack of the right kinds of foods (which is why you want to diversify their diet and feed them only quality food with less fillers). On rare occasions the reason could be a fluke on the eye but sometimes its a simple as physical damage to the eye by running into something in the pond. Both eyes can have pop eye or just one, either is possible.

      Treatment: Treatments for cloudy eye are a medicated koi food formulated to handle fungal and bacterial issues called Medi-Koi and or Mela-Fix. Mela-Fix is actually an oil extract from the Melaleuca tree mostly occurring in Australia and it has natural anti-bacterial properties.

      -good luck

      Reply
  52. In the last week. We have lost many large koi. We have noticed they are scrapping their belly on the bottom of our indoor pond. We don’t see any strange markings or discoloration on them. Other then they are extreamly slimy. Any ideas as to what to do to save the rest of our fish

    Reply
    • Sounds to me like parasites. They will often scrape the bottom (flashing) to rid themselves of it. Flukes are often the culprit in these cases but usually the water chemistry must be such that flukes and other parasites are able to thrive. So I would check your water chemistry and be sure that you don’t have an excess of chlorine because that will cause flashing too but you want to make sure your ammonia isn’t off or pH balance is where it should be. To treat flukes here is an excerpt from my site:

      Treatment: You can quarantine but it is likely that your entire pond is afflicted with the flukes or their eggs so you can treat with medications like Aqua Prazzi, potassium permanganate or Fluke Solve (both AquaPrazzi and Fluke Solve have the same active ingredient; “praziquantel”).

      Reply
  53. Have 11 kio and are swimming side ways sometimes I think it is ick and treating them for it could this be something I don’t see anything on them but can’t get a close look have some orange and there seems not to have anything on them any ideas the water test a perfect

    Reply
    • Most likely that is a swim bladder problem brought on by a bacterial infection. You could try to increase salt concentration in your water to start attacking the bacteria. You could also feed your koi Medi-Koi as it is specially formulated for internal bacterial infections.
      -Grant

      Reply
  54. One of my fish has a gill cover that bends out at the edge. He seems fine and eats as much food as the rest and does not look ill at all. Is it just a malformation from birth? This fish is the off spring of two of our other fish.

    Reply
    • this kind of thing is not exactly common and generally I wouldn’t worry too much about it. A bit of flair in the operculum has been associated with periods of low dissolved oxygen in the water or even overcrowded conditions. One of its main jobs is the ability to close and keep “stuff” out of the gills but if you keep your water chemistry in check and parasites down you’ll be okay.

      Update:
      Thanks Grant, that fits perfectly as this fish managed to get into the frog pond for a while at one point, which is not aerated, so that would be the reason.
      Many thanks for your time.
      Ray

      Reply
  55. My baby koi has a white film looking substance on her, for about a week now and recently she been spending time on the bottom of the tank facing the glass. Any suggestions would help a great deal

    Reply
  56. Roberta says:
    August 28, 2014 at 7:53 pm
    My Koi has red spot on the fin and the tail.
    What should I do?
    Thank you.
    Roberta

    Reply
    Koi-Care staff says:
    August 31, 2014 at 1:30 am
    Roberta,
    You need to quarantine your fish, first off. Then increase the salt concentration to 0.5%. You will want to treat the water with mela-fix. Make sure your quarantine has good aeration and filtration. Your pond water probably has an increase in excess nutrients that allow bacteria, like the one most likely causing the red spots, to thrive. You will want to test your pond water on a regular basis and watch for ammonia, nitrites, nitrates. You can even do something like microbe-lift to boost your beneficial bacteria load in your filter media.
    Good luck, Grant

    Reply
    Roberta says:
    October 24, 2014 at 5:26 pm
    Thank you so much for your reply, Grant.
    I have a 2500 gallon size pond. So far, one of the local fish guy came and added #5 of salt then some blue liquid…..Proforma C? It has been about 6 weeks and the poor fish still has the red spots (none of the other 5 has the problem). However, it eats and swims around normally. I have been keeping up the level of water and cleaning the filter system where at least 10-20% fresh water is added.
    Should I dump some Tetra Pond Fish Treatment in or more salt or ? There is no way I can quarantine that fish.
    Thank you Grant.
    Roberta

    Reply
  57. My 13 koi (very large and have had babies) have been in a big outdoor natural pond for 10years (20mx15mx2m) with black native kookas . 1 fish has lost a eye has a hole where it used to be .Its hard to tell for sure but 1or 2 of the others appear to have white eye brows .What can be done in this situation
    regards tony

    Reply
    • Tony, the koi with the missing eye could be unrelated to what sounds like ich or fungus on your other fish. That koi may have been the victim of a wading bird looking for a meal.
      So if its ich here is an excerpt from my site on treatment:

      There are a couple of widely used methods to treat ich. The first one requires the koi owner to increase the salt concentration of the pond or quarantine tank to about 0.5% over a period of days. At the same time increase the temperature of the water gradually to the high 70’s F while increasing aeration. This is an effective and cheaper way to deal with the ich protozoan. The second method is a tried and true method for dealing with parasites in general and involves malachite green and formalin. Using both simultaneously is definitely going to be effective against ich but you may be able to simply treat with malachite green alone. For short treatments in quarantine, one could do a quantity of 1.5 mg of malachite green for every liter of water for up to 1 hour (or 6mg of malachite green for every gallon of water). Always wear gloves when handling both malachite green and formalin.

      If its fungus:

      Treating Fungus: Fungus can be removed by gently rubbing the area with a cotton swab while the infected area must be treated with an antibiotic or antimicrobial cream immediately afterwards.

      Reply
  58. I have a 2500 gallon size pond. So far, one of the local fish guy came and added #5 of salt then some blue liquid…..Proforma C? It has been about 8 weeks and the poor fish still has the red spots (none of the other 5 has the problem). However, it eats and swims around normally. I have been keeping up the level of water and cleaning the filter system where at least 10-20% fresh water is added.
    Should I dump some Tetra Pond Fish Treatment in or more salt or just let it be? There is no way I can quarantine that fish, too big.
    Thank you Grant.
    Roberta

    Reply
  59. My koi fish has a small cotony patch with a thread like worm inside on its tail..otherwise it apears fine, sum times it jumps out ovr water surface
    Added blue medicine to aquarium
    suggest sumthing

    Reply
    • potassium permanganate does a good job on most parasites but sometimes you need to add formalin. It depends on the type of parasite though.

      Reply
  60. Iam from india , i have just build a pond indoor and let some kois ,added uv fillters for it . but koi are starting to die one by one . i see them rest at bottom of pond and die . in some fishes i can see they lost their scales . pls help . thanks in advance.

    Reply
    • You have UV filters but what about biological filtration and mechanical filtration? What is your water chemistry like? There’s a lot of potential explanations for the death of your koi…

      Reply
  61. i have a new koi pond w/ 34 pieces koi…after 3 days only 2 survive and 32 were dead…please help me what went wrong and any suggestions on the proper maintenance of koi fish pond for them to last for a long time…

    thanks very much

    Reply
    • That sounds like you have too many koi in a pond that can’t sustain that many. Most likely you have a extreme build up of toxins like ammonia and that caused your fish to die. You need good filtration for starters. If you are just starting out you may want to consider the book I recommend on my site (http://koi-care.com/)
      -Grant

      Reply
  62. I have a large koi which is about 20 years old and is now floating upside down and when the fish swims to the bottom of the pond it floats back to the top can you help!

    Reply
    • It sounds to me like a swim bladder issue or more likely an internal bacterial infection. You will need to do antibacterial injections if that’s the case. You will probably want to quarantine this fish.How is it eating?
      -Grant

      Reply
  63. I have a small to med koi in a 30 gallon aquarium with 3 other fish. The water has been yellow and gets cloudy fast, what causes that?

    Reply
    • Sounds like you have a build up of ammonia. You may want to make sure your filter is up to speed with its bacterial colony on your filter media.

      Reply
  64. I have several koi in an aquarium. They average 4-8″ long. All seems well but I have 1 that has no scales to mention. Along his dorsil fin looks fine and his belly side is fine. Other than that all he has is skin. He doesnt appear sick. The others are fine. Anyone havea clue why I have a BALD KOI.

    Reply
    • Doitsu are known to be scale-less. Not sure what you have in the mix but that may be one of them.
      The other option is an infection in which case you will want to treat with an antibiotic ointment.
      -Grant

      Reply
  65. We moved into a home with a koi pond. One of the fish has very bloated sides. Has behaved normally until the last day or so and is hovering near the bottom. Is she full of eggs or should I isolate him/her?

    Reply
    • Prob. too early to be eggs -sounds like an air bladder issue or (most likely) an internal infection. What is the state of your water chemistry? Infections typically arise due to poor water conditions.
      -Grant

      Reply
  66. Hi i purchased 5 new fish 7 days ago but 2 of them have got cloudy eyes and it looks like a flaky skin of white and one is brownish ,please could you help me with what might be wrong .Thanks
    allen broughton

    Reply
    • Allen, here is an excerpt from my site about cloudy eye:
      Cloudy Eye

      Cloudy eye is somewhat uncommon but it can occur. This malady is typically a symptom of something else going on rather than something attacking the eye specifically. Some causes are bacterial infection, a cataract or even lack of the right kinds of foods (which is why you want to diversify their diet and feed them only quality food with less fillers). On rare occasions the reason could be a fluke on the eye but sometimes its a simple as physical damage to the eye by running into something in the pond. Both eyes can have pop eye or just one, either is possible.

      Treating Cloudy Eye: Treatments for cloudy eye are a medicated koi food formulated to handle fungal and bacterial issues called Medi-Koi and or Mela-Fix. Mela-Fix is actually an oil extract from the Melaleuca tree mostly occurring in Australia and it has natural anti-bacterial properties.

      A good plan with new fish is to quarantine for many weeks prior to introduction into your pond. You just never know what fish have.

      Reply
  67. We have 9 Koi about 2 years old, in 800L outside pond.Today I noticed that nearly all of them has like grains of salt attached to they scale head, fins and some of them have like a pinkish patchy growth. Apart from that ,they seem to be fine. I read on your web that it could be ich and carp pox.We had in a last 2 weeks hot days and cold nights.Could that be the cause and what treatment would you recommend for that. We live far north NSW Australia.

    Reply
    • G’day,
      I believe that, from your description, it sounds like ich and carp pox. Carp pox doesn’t have a lot of solutions -its just part of pond life and usually comes around when the water turns colder. As for ich -its prob. the most common malady affecting pet fish. My ich treatment recommendation is same as is found on my site -you’d be amazed at what salt can do.

      There are a couple of widely used methods to treat ich. The first one requires the koi owner to increase the salt concentration of the pond or quarantine tank to about 0.5% over a period of days. At the same time increase the temperature of the water gradually to the mid 80’s F while increasing aeration. This quarantine should last 2 weeks and is an effective and cheaper way to deal with the ich protozoan. The second method is a tried and true method for dealing with parasites in general and involves malachite green and formalin. Using both simultaneously is definitely going to be effective against ich but you may be able to simply treat with malachite green alone. For short treatments in quarantine, one could do a quantity of 1.5 mg of malachite green for every liter of water for up to 1 hour (or 6mg of malachite green for every gallon of water). Always wear gloves when handling both malachite green and formalin.

      Reply
  68. One of my fish died, but the cause is unknown. It was swimming around the edges of the pond for a while. We left the pond to do other things for a while, came back and the fish was dead. The only thing that stood out were the red markings around the fish’s throat/mouth.

    Reply
    • red marks may be injuries from wading birds or perhaps an internal bacterial infection (usually it will be red streaks)

      Reply
  69. We have a koi pond. Koi and goldfish for 3 years. We have had a lot of rain lately. The fish started acting weird-not eating when fed, laying on the bottom or gasping at the top. Yesterday 2 small fish died. The water is testing ok. Today 4 more have died. We treated with Primafix and tonight changed out water. Not sure my last two large Koi and one small baby is going to make it.
    We have a corkscrew willow tree next to the pond. I novices it is losing leaves. They are turning yellow and some branches are bare. We were told it has Yellow Blight or Black Canker. Could the falling leaves have caused this?

    Reply
    • As far as I understand, both blights and cankers in plants/trees are caused by fungi. Fungal infections in koi are typically obvious as it appears as white and fluffy growths. If your water tests out okay then you may have had something enter the pond along with all the rain runoff you had recently. Perhaps some chemical fertilizer or pesticide got washed into the pond via the runoff? If they are gasping that usually means their gills are compromised in some way such as high ammonia that may be burning their gills but it could also be low dissolved oxygen, which i doubt is the case. With foreign chemicals in the water you may see behavior like gasping but its hard to tell as there are many chemicals out there that could end up in runoff. Unfortunately, I don’t have any solid answers for you on your koi issue.

      -grant

      Reply
  70. One of my koi is having difficulty swimming and its body seems permanently bent. It’s also breathing a lot on the pond’s surface. It’s not schooling with the other koi and seems to want to hide from them in plant growth on the sides of the pond.

    I don’t see this bent body syndrome mentioned in your list of diseases. Any thoughts? Thanks.

    Reply
    • What comes to mind is scoliosis which has several causes the most likely of which is bit. C deficiency. However your other koi don’t have so its possibly a swim bladder issue. Maybe an internal infection causing the swim bladder to not deflate properly.
      If its scoliosis then an increase in foods with ascorbic acid would def. Help but if its a swim bladder condition then you may need to antibacterial injections. In the short term, You could isolate this fish and feed medicated food like Medi-koi in addition to foods with vit. C to cover your bases.

      Reply
  71. I know we have high nitrates and nitrites, but am not sure how to treat this. I read on one your earlier replies that the water should be check for dissolved oxygen. Can you tell me how to do this, please?

    Some of my koi have been staying in one shaded spot, right by the oxygenators and the Laguna filter we have in the pond. The filter has a back flush and uv light. There are two nets with parrot feathers, lettuce, and hyacinth, they were eating all their plants.

    They do swim around and are eating fine, but one of my bigger ones (16″ measured without tail) stays there a lot of the time.

    Can you help? I want to make sure it doesn’t escalate.

    Thank you in advance if you can help us.

    Amber

    Reply
    • you shouldn’t be concerned with dissolved oxygen in your pond unless you have no aerators and its particularly hot and your pond is especially shallow. There’s always going to be exchange of oxygen at the surface-air interface too. More importantly is dealing with your high nitrites. You may want to analyze how much you are feeding out and that there is not a lot of extra uneaten food. Secondly, how is your filtration? You may want to look at giving your filter media a boost with something like Microbe-lift PL -those beneficial bacteria are going to be the workhorse when it comes to assimilating nitrogenous waste. You may also want to consider some water changes to flush out some of those nitrites.

      Reply
  72. My koi has like a white stuff on her but really does not look like ich and it has like a white cloud over its eyes. Its stay around the top and open and closing its mouth alot. Help she is my baby.

    Reply
    • This is from my site on Trichodina. If you don’t think its ich then this affliction may fit the description.

      One of the easiest protozoan parasites to see under a microscope, and subsequently confirm your fish is infected, is Trichodina. An infection of this parasite can be detected by a gray-white opaque appearance on the body of infected Koi. Trichodina is a warm water parasite and can survive in the water for a considerable amount of time without a host. Visually, they are perfectly round with hundreds of little hooks that look like cilia. It rotates continuously as it moves through mucus, causing damage to the Koi’s tissue. This parasite attacks both the skin and gills of your Koi. Infected fish also often show symptoms such as flashing, rubbing and lethargy.

      Treating Trichodina: Treat this disease with a five day course of increased salinity (0.5 to 0.6%). Due to increasing tolerance of some organisms to salt treatments a course of formalin may be necessary.

      Reply
  73. Hi, i noticed that my koi started having reddish spots (flat) on its body and it has became more and more restless. Sometimes it will jump up and (luckily) land back into the pond and most of the times, it would swim around the pond and rub its body against the side of the pond. This has been going on since a few days ago. Isit possible that this was caused due to adding 4 new koi into the pond? The pond is cleaned regularly and I have added anti bacteria and anti fungi medicine, and also added in salt but it doesn’t show much results. Please reply ASAP… Thank you for your time.

    Reply
    • sounds like anchor worm and yes, it is likely newly introduced fish could have brought that in. you really want to quarantine fish for several weeks prior to introduction to your pond. from my site:
      Treating Anchor Worm: They can be removed using tweezers or other small pincers. After removal, rub some Neosporin on the infected area. Use Dimilin, Dylox or Lufenuron to treat the pond. Though Dimilin is probably your best bet for clearing up anchor worm there are other products out there that have a good track records as well and those include ECORX and Anchors Away.

      Reply
  74. one of my fish has like a very fine pond weed on it , which is now falling of and underneath the scales have gone it seems to be on three more fish it just looks like a fine blanket weed I have tested water seems ok and doing water changes. Is it possible this is a fungus disease.

    Reply
    • sounds like fungus to me. an excerpt from my site on the matter:
      Some causes of fish infections, such as fungal hyphae or spores, require a microscope to see them. Mild or moderate infections can be treated and possibly cured if they are caught early. These types of fungal infections are not typically contagious and usually only a single Koi becomes infected.

      Treating Fungus: Fungus can be removed by gently rubbing the area with a cotton swab while the infected area must be treated with an antibiotic or antimicrobial cream immediately afterwards.

      Reply
  75. One of the fish has what looks to be welts or a wrinkled look in its spine and tail area. For three day the fish has been sitting under the rock waterfall straight up and down and look to be breathing/gulping semi fast.

    Reply
    • Those symptoms don’t sound familiar to me -what is your water chemistry like? Any other strange behavior from other fish?

      Reply
  76. I have two Koi. One (Orange) has discolored spots all over his body. Some are the size of a quarter. He also has discoloration on his tail. The other has no discoloration but they are both laying on the bottom of the pond and are not eating. The orange ones eyes are almost half closed and they will randomly swim real fast around the pond and then lay back down. I have treated for two days now with Melafix and Pimafix. They do flash every once in a while. I had my water tested at my local pet store and they said the water was perfect. I have introduced 4 new small Koi’s into the tank but all my Goldfish are perfectly healthy, eating and no discoloration. Any suggestions?

    Reply
    • most likely if you had no problems before and then started having problems post-introduction of new fish you inadvertently brought something in with the new fish. In this case it sounds like some sort of parasite. From the description it sounds like argulus (fish lice). This is from my site:

      These unwanted invaders have eight legs and rounded bodies. They also have to big suckers which are used to attach to the fish. Their appearance leads to their nickname, “fish lice”. These parasites can cause considerable irritation to fish and can lead to bacterial infections. The irritation will lead to flashing and rubbing which should tip you off that something is wrong and the koi are trying to get some relief.

      Treating Argulus: As with anchor worm, treatment will consist of Dimilin but another product also works as well, Lufenuron. You should see positive results in a matter of days.

      Reply
  77. Hi there, I have a ghost kio @ 20yrs old and have noticed today that its body is covered in what I can only describe as a mildew like coating on its scales and all fins, no white cottenwool effect, no ulcers, no redening on its body. This has appeared over the last 48hrs. Any ideas please as i would hate to loose it after all these years. Its in a pond that is @ 1000gals with other kio and goldfish.

    Reply
    • I can only think of two possibilities: velvet disease and ich. Fungal growths usually only affect areas on koi that are already afflicted with an ulcer or another similar malady

      Reply
    • Here is an excerpt of an article from my site on pop eye:
      Pop Eye

      Pop eye is also called exophthalmia and is really not linked to any one illness but is more of a symptom of something more. It is a direct response to an excess of fluid or possibly gasses built up behind the eye which then cause the eye to bulge is distend. There could be several things that could cause this to happen. Sometimes this malady is caused by a bacterial infection while other times it is due to trauma from running into the side of a concrete pond.

      Treating Pop Eye: The best course of action is to immediately quarantine the fish and do a light salt bath. You will also want to greatly reduce feeding and how much you give it. You will also want to do 25% water changes daily and monitor water quality on a regular basis.

      Reply
  78. 1. How and where can a person obtain the supplies necessary to perform antibacterial injections? Is this something I can do or do I have to bring the fish somewhere else?
    2. Is it prudent to treat the water with medications that would prevent the infection of fish prior to the onset of symptoms?
    3. I have a large Koi aprox. 10yrs. old that suddenly lost it’s ability to swim vertically. It is staying on the bottom of the pond laying one it’s side. Don’t see any external signs of disease except the eyes look larger. I’m not sure what medications would be best to treat this fish with. Can you advise.
    Thanks,
    Dave V.

    Reply
    • Dave,
      1) you should be able to get something like Baytril at a vets office and if you can find someone experience to do it that would be preferrable (there are different ways and locations to inject antibiotics and its best to have someone do it that has that kind of knowledge)
      2) it may not be the best idea to “pre treat” as it were due to the danger of bacteria building up a resistance by being exposed to it all the time.
      3) sounds like it could certainly be an internal infection and bulging eyes are a symptom of that.

      Reply
    • Firstly, its important to remove the elements causing the stress but there is a product by API called PondCare Stress Coat Water Conditioner. It will help renew the slime coating that can suffer during times of stress.

      Reply
    • Could have gotten an injury that healed strangely. Are you sure this is a new thing or was it like this since it was young?

      Reply
  79. I have a large white koi that I have had for about 10 years.i noticed one of her sides looks almost like a reddish tint under its scales. Almost like a bruise but red.

    Reply
    • sounds like it could be psuedomonas bacteria infection. You will need to get some Baytril injections. Its best to get someone with experience to do this if you are not familiar. You will also want to quarantine and feed medicated food like Medi-Koi.

      Reply
  80. Hi over the past week alot of our koi have become ill, they are all hiding around the plants at the corners of our pond, not swimming much and some have like a white whispery coating whilst others have a green moss coating,our biggest fish started swimming on his side knocking into the walls of the pond and has now died, we have also noticed one was bleeding from his gills, some also look like they have fin rot, some gold fish also have these symptoms can anyone help please a total of 5 carp have now died

    Reply
    • It sounds very much like you have water quality issues bringing all these maladies on. Fin rot and a green mossy coating (fungus) don’t move into your pond unless you have higher ammonia or nitrites etc. Have you done any water testing?

      Reply
    • An excerpt from my site:

      Ulcers on the skin of your fish result from bacterial infections that form on scales, causing them to become red. The infection causes holes, or ulcers on the exterior of the fish and will eventually result in loss of scales if left untreated. These ulcers are most often caused by poor quality of the water in the pond coupled with depressed koi immune systems in Spring get attacked by parasites carrying bacteria.

      Ulcer Treatment: Maintain a healthy, clean pond and treat ulcers with a topicalantibacterial such as Panalog to stop the bacteria in their tracks.

      Reply
  81. My koi has a tumor like blob that has broke through his scales under his dorsal fin. He still eats and swims around but does not use that fin. What should I do, Please help!!!

    Reply
    • Does it appear pinkish and look like melted wax?

      Yes it does. Do you know what it might be? Do you know of any solutions to help him?

      That sounds like carp pox. It’s not fatal. I’m on the road right now but if you go to my site there is a write up on it under diseases

      thank you so much!!

      Reply
  82. Hi my koi was sitting on the bottom and after some water changes and some tetra medicine he slowly swims around and occasionally stays on top i guess for air. By the way he’s not eating. I would really appreciate if you respond thanks. P.s
    By the way i had a extremely bloated all over chiclid in the tank that would sit next to my koi in the bottom.

    Reply
    • honestly, there’s a lot that could be going on here. Is your koi now bloated or just the cichlid? bloating suggests an internal bacterial infection and if your cichlid has it in the same container/pond then you probably have some water quality issues that is allowing one or more beaties to thrive in your pond and subsequently attach your fish. notice any sores or ulcers?

      Reply
  83. Backround – 5000 Gallon Pond COMPLETELY enclosed, 7 foot waterfall covered roof.
    All water parameters are within normal range.
    Occupants – 3 Kois – 26 to 30 inches long weighing 9 or so pounds, age 14 years
    Occupants – 4 Kois 20 to 25 inches long Weighing 7 pounds or so ,age 14 years
    Occupants – 3 Kois 15 to 20 Inches long weighing 5 pounds or so, age 10 years.

    Problem: I went out this morning and one of my small butterfly kois front right fin is completely BLOOD red. Slim coat looks good, eyes are clear, respiration seems fine. Everyone else looks fine no redness to their fins. Everyone ate this morning.

    Added Salt today. But I am worried. These fish are part of our family I cannot find ANYTHING online that looks like this. Is not flukes or fin rot or lice. She has no ulcers or sores anywhere but that fin I have never seen a kois fin so red. It almost looks like it is bleeding from her body to her fin at the spot they connect.
    I am setting up the QT tank (is 500 gallons so it takes a lil bit ARGH) now.

    Suggestions? Ideas?

    thanks!

    Reply
  84. I saw that 1 of my koi had white fluff on his body, was not swimming and segregated form the rest. I have put him in an aquarium, treated as directed with Herbal Relief for Bacterial and Fungal Diseases ( National Geographic ). I gave him that last dosage 2 days ago. Today, I did a 25% water change. He is not eating and still doesn’t look right al though vastly improved from a week ago. Any advice?

    Reply
    • white fluff could be a few things like fungus, costia, ich ( Ich being the most common). The quarantine tank is good but you may also want to gradually increase the salinity to 0.5% over several days. This will make it difficult for the ich protozoan and give your koi a bit of osmotic relief (towards the lower salinities). You can also try malachite green and formalin (don’t use if you have already added salt though.) For fungus and external bacterial problems mela-fix is great. if its costia, you can again use malachinte green and formalin.

      Reply
  85. Thank you for all the advice. After reading, was able to look for Melafix. The koi is doing so much better now. May have been a swim bladder problem. I medicated the entire 250 gallon pond for the other koi, too. Since temps went to 29 overnight, I have a pond heater floating in there. The sick fish is now in a large tub, soon to be transferred to my bathtub (at the suggestion of my husband!) where it will be able to actually swim, when ready. Fish is 24 inches long, so presented a quarantine problem (use a huge rubbermaid tub that was rinsed and sun dried).
    Thanks, so much!

    Reply
  86. Hi there,
    I’ve got, (aside from an orange blotch on her face)a pure white koi and I’m not sure of her exact age but, I’ve had her for well over a year now. I recently bought two more koi to keep her company as the other original koi I had in with her passed away due to a problem he had with his mouth and he couldn’t eat properly. At first I was glad I did so because she seemed a lot more lively and happy with her new friends.
    About 1-2 days later though, she has developed a bright red tinge all through her body, tails and fins. I thought she may be changing colour but quickly thought otherwise because it looks like her scales and base of the tail and fins are “bloody” if that makes sense?
    I took a sample of my water to the place I got the other two and he did a test of my water and said to up the salt as it was low, but everthing else was fine. I’ve done so but she doesn’t seem to be getting better at all. If anything she’s worse. Her swimming is starting to go downhill and she seems very lethargic.Though she’s using all of her body and fins so there’s no loss of movement. She’s eating fine too. Though I’ve noticed half of her face (left side) has darkened in the red and the left gill she’s not using as efficiently as the right. The blood red tinge has gotten worse and I’m all out of ideas on what to do. She’s not in a pond yet but a 120L tank. ANY suggestions or advice I will gladly take because I love this damn koi so much and I really don’t want to lose her 🙁

    Reply
    • it sounds like the likely culprit is Bacterial Hemorrhagic Septicemia. If I am correct you will need to do Baytril injections (best done by a vet if you have no experience with that sort of thing). My guess is that your newly introduced fish didn’t get quarantined or for long enough prior to being added to their new home. New fish can often introduce new diseases

      Reply
  87. hi, i have about a 1000 gallon pond with 8 koi. I noticed 2 had white spots on their fins. I began treating with an ich remover immediately and increased salt levels. They now appear fine but other koi then began showing different signs. A young one (6mo.) now has the bent spine look accompanied by one 1/4″ long looking blood vessel on his side. Another approximately 3 years began looking like he had “glass” covering some scales. I lifted him out of the water a then saw his scales were actually filled with a liquid which squirted out under light pressure. This same fish also developed a “small” (1/8″) white spot on his eye. It is now around 50 degrees water temp.
    I’m at a total loss in treating this. I hope it’s not contagious as i have no way to quarantine and fish. Please Help. Happy Holidays!

    Reply
    • if you had ich to begin with it suggests that you could have other nasties in your water as well. All the above stem from issues with water quality so my first question would be: have you checked the usual suspects with your water chemistry? The fluid filled scales is not something that comes up with koi owners much but going from memory I believe that would be some stemming from a bacterial infection. One thing you could try is feeding with a medicated food like Medi-Koi. You increased salt levels: to about how high? You can get away with levels as high as 0.6%. I would keep treating for ich. Are you using Melafix for that. Bent spine in most other cases would likely mean the fish is deficient of ascorbic acid but considering everything else you may have a fish with some sort of internal bacterial infection (possibly of the swim bladder) causing it to take on a bent shape. Normally, you would immediately quarantine, and do water changes and start ramping up your benefical bacterial loads on your filter media but that won’t do much good in these kinds of temps. Sorry i can’t be more help here-at cold temps it becomes more difficult to treat this kind of stuff but as I mentioned I would start with the Medi-koi

      Reply
  88. hi!
    i have a koi fish in my aquarium inside the house with the size of 18″x 36″x 18″ which content of 15 koi fish, i noticed 5 of them keeps on gliding on the bottom of the the aquarium with their side and near the gill. please response on what treatment i will do?
    thanks….

    Reply
    • it sounds like they are flashing on the bottom in attempts to rid themselves of irritating parasites. It helps to know what kind of parasite you are treating before you treat. See anything on their scales?

      Reply
  89. One of my friend complaint that his koi spit his food. It just swallow the food and then spit it. He sent me photo of his koi and I see reddish in the skin and the tails also like the veins are getting red too. what type of disease it is and how to treat it?

    Reply
  90. I have a 180 litre tank.I have 2 koi.4 goldfish,2 shubunkins 1 comet and 2 silver rudd.I have a problem with the 2 kois.It seems they have gill problems and keep flashing against the internal glass thermometer and dash from end to end of the tank.It’s not all the time and the other fish are perfectly well.If it’s flukes or parasites why are the other fish okay.There’s plenty of aeration and water parameters are spot on.I have plastic plants around the tank and the fish are quite small.Please could you suggest what is wrong as it’s really worrying me and I care about all my fish.Thankfully all my pond fish are fit and well & always have been.Many thanks.Sincerely.Liz Breton

    Reply
  91. Please help me my carp fishes are dying….the have become ill…i havr4 feet aquarium…they are not floating and are sitting dull at the bottom of tank….i have given them flucka150 antifungal

    Reply
    • its possible they have an bacterial infection in which case you would want to give them something like Medi-Koi medicated food. However it really could be a lot of things wrong. Obviously the fish you put in from your friend brought in some disease or parasite -you always want to quarantine new fish first.
      -grant

      Reply
  92. Please help me!!!!! I found one of my large koi floating on his side with, what I assume is a fungus, on all fins and on the body. I only noticed this because we had some warmer days and the ice began to melt. He is still in winter mode though so there is no movement. Mouth opens once in a while and his gills are still moving but very slowly. What should I do? What could it be? Any help would be appreciated.

    Reply
    • A commonly occurring fungus in cold water is saprolegnia and can be effectively treated with potassium permanganate. I would quarantine if you can to treat. Also, you may want to check on your water chemistry as fungus shouldn’t occur unless something is up with your water (though it could be that your fish is compromised due to injury thus allowing the fungus to move in).
      -Grant

      Reply
  93. Hi– I have a younger black Koi who now has a single whitish spot on his back towards his head. It has irregular edges,is smooth, and after watching him for two weeks , nothing new , spot is unchanged. He has normal activity, is eating fine, and I’m not seeing anything else going on with him. I’ve got him quarantined and he’s very unhappy with me. Is this Pox?

    Reply
  94. I have a tiny koi seems to be losing color just on her tail an has fluffy fungus hanging from tail fins only just seen it as she is about 2-3 inches I spotted her hovering at the top of the water last night! Also other bigger fish seem hyper all of a sudden could this be linked?

    Reply
    • a couple things come to mind: a fungus of some description and epistylis. You could start by raising the salinity to about 0.3%. In doing this you can rule out fungus if there is no improvement. If it is fungus then there are options like Melafix and Pimafix however there is also the shotgun method like Microbe-lift broad spectrum which would deal with both fungus and parasites. The hyper activity is probably not linked. Is it full moon? Is the water getting warmer? Those can have an impact too.
      -Grant

      Reply
  95. Please help me and my two Koi fish !!

    1. Earlier, the fish would rush towards food, but now they don’t eat much.

    2. We changed the water of the fish-tank 6-7 days ago and today all of a sudden the water turned blurry and both the fish have dark and dirty spots and looks like the are looking lazy.

    3. My two koi fish are swimming with their head up and tail pointing downwards ideally they should swim side ways.

    Thanks and Regards,
    Juhi

    Reply
  96. I was wondering why a koi would be by its self on the bottom of the pond. It’s been doing this for a few weeks now. Not sure what to do. Got some baby koi in the pond and all the other koi in the pond are swimming around

    Reply
    • There could be a host of reasons -if everyone else is doing well then you probably don’t have parasite or water quality issues. Perhaps an air bladder issue/infection that may be causing a buoyancy issue?
      -Grant

      Reply
  97. Please help me and my two Koi fish !!

    1. Earlier, the fish would rush towards food, but now they don’t eat much.

    2. We changed the water of the fish-tank 6-7 days ago and today all of a sudden the water turned blurry and both the fish have dark and dirty spots and looks like the are looking lazy.

    3. My two koi fish are swimming with their head up and tail pointing downwards ideally they should swim side ways.

    Thanks and Regards,
    Juhi

    Reply
  98. Our koi pond has lost about 5 fish in the past three weeks with no signs of symptoms from your above article and we hadn’t lost a fish for the whole first year. But as of a few days ago, two of our larger koi have developed a few shiny scale shaped spots on their sides. They are still eating normally but seem a little less active than before, any idea of what this could be and any ways to prevent further fatalities?
    Thanks,
    -Drew

    Reply
    • Diagnosing these kinds of things can be challenging but typically most health issues are rooted in water chemistry and we are getting into warmer weather which is conducive to many kinds if parasites. So firstly, what are you seeing when you test your water with a test kit (ammonia, nitrites, nitrates etc)?

      Reply
  99. At the edge of my koi’s tail there it is a dark red and just recently I noticed that there is a red spot on the body near the tail. The koi tail has been turning red quite a while ago. The fish is also really slow and looks weaker than some other fishes. Can you tell me whag is it and what I can do about it?

    Reply
    • It’s a little tough to definitively diagnose but one thing that comes to mind is elevated ammonia in your water. I would check that along with nitrites and nitrites. Another possibility is pseudomonas bacteria infection. Here is an excerpt from my site:

      Pseudomonas bacteria: Like its cousin, aeromonas, this bacteria is also associated with ulcers and fin erosion.

      Treating Pseudomonas: Infections of this nature will require an injection of Baytril.

      Reply
  100. Hi

    I recently diagnosed my koi carp having trichodina. I have treated the pond with formaldehyde twice now and I am into day 3 of the second treatment. I have also salted the water. The water levels are good and I’ve increased the aeration. 9 of the 11 fish are eating alert and look good. But 2 have not eaten in last 7 days are lethargic and tend to sit near surface of water on their own… not sure what to do now? Whether to wait further 7 days and treat the 2 sick koi on their own with pp or do another formaldehyde treatment in 4 days? Please help

    Caroline

    Reply
    • I’m assuming you mean formalin and not formaldehyde? It is not recommended that you have a salt level of 0.1% or more when using formalin. Formalin also increases in toxicity when the water is more acidic, very warm or both. I would try to treat the other two fish in their own quarantine but this time with 5 days of full dose salinity 0.5 to 0.6%. Formalin is harsh stuff so if you can go the salt route first I think it would be better for the fish.
      -Grant

      Reply
  101. I have a small pond with koi and goldfish in it. Yesterday my biggest koi died suddenly, he seemed fine the day before. He had a red spot on both sides behind the gills and the fins looked red near his body, also had blood on it, maybe coming from the gills. The other fish seem to be ok, but concerned what killed the koi. I have had the pond about 5 years and haven’t added any new fish lately.

    Reply
  102. Hi, while I was on holiday, my pond suffered a catastrophic failure where I lost most of 3 cubic meters of water, my son came and put some water in with conditioner, but was unable to repair the leak, so he move them to his house, and kept them for a week in the only thing he had, a small tank which was too small for the fish that had survived, they have been returned to a temp nursery tank, with salt a high as I dare 3oz.. but during all this the stress was horrific for them.
    they started with whitespot, at my son’s house which became very bad, some have the white spot covered in algae, but this has peeled off like a carpet, leaving flesh exposed, I have used aloe Vera, fresh start conditioner to sooth the wounds, and raised the salt level, and brought the tank temp to 23c, and given them medi koi food.. and the tank has a large filter for its needs with its own uv.
    the fish have calmed down now and tend to run through the air streams in the tank, which may mean the repairing skin is itching, or I have another problem, I am doing regular water changes.. anything else I can do ?
    kind regards
    Paul.

    Reply
  103. Hi, I moved into my new house 2 months ago. We have a pond with approx 8 medium koi fish, 7 outdoor fish and 3 rather large koi fish. Last week, one of the large koi fish died – since then, we’ve changed the filets, ensured a sufficient amount of froth is being produced from the fountain, and make sure we’re feeding the koi fish as and when we should. After assuming we made adequate changes, this morning we woke up to find the second of the large koi fish had died. There seemed to have been red ‘rashes’ on the body, just like the fish that died last week. After contemplating, I did notice the second large koi fish hadn’t ate for over 6 days. What could have been the problem and also, are the rest of my fish in danger? Although they all seem to be ok as they are all eating and acting lively.

    Reply
  104. My very large koi was standoffish and very easy to pick up,witch never happens
    Yesterday I noticed she was very lethargic and when I picked her up her skin was extremely mushy and soft. Today I get home from work and she swimming in her gut has exploded and she’s rotting from the inside out please tell me what this is. I have 8 in my pond is 43 feet long and 27 feet wide crystal clear and everything has been healthy and still is except for her she died today

    Reply
  105. I sure could use some help. My koi has been subject to water high in ammonia that I have been battling with for the last 4 months. Water company protocal has changed. While I use a filter to remove chlorine the ammonia is left behind. I have switched to filling indoor pond with spring water and am getting some stability now. Ammonia now .50 and PH fluctuates between 6.2 to 7.2. I have been adding buffer to help with PH crashes. Through all of this now my koi has lost weight and appears to be bent a little. Appetite is slowly improving. I am noticing (hard to see it) a redness and lifted scales behind anal fin on left under side of fish. Almost looks like waste is getting caught on scales there. What is it and how do I save my fish? I have been adding some salt to and water temp is around 74 degrees.

    Reply
    • Yeah, ammonia is not good. What kind of filtration do you have? One of the most common problems I talk to folks about is dealing with nitrogenous waste via beneficial bacteria. Water quality is usually at the heart of just about every koi health issue and an easy way to deal with ammonia, besides not over crowding and not over feeding is populating your filter media with beneficial bacteria ( something like Microbe-lift PL). Another thing that can cause big problems is big pH swings. High or low pH is not as much of a health issue as rapid changes in pH are. The pH scale is logarithmic not linear so any little shift translates into a big shift. One way to deal with that is by putting something into your pond made of calcium carbonate. That could be a cinder block or landscape rock of that composition. The calcium carbonate will help buffer those big shifts.

      Reply
  106. I find your site very helpful but I didn’t see any malady with symptoms of nose on bottom and tail elevated able to swim and no obvious wounds can you please expand on this symptom for me

    Reply
    • Is the belly bloated?

      No it is not. The koi looks fine other then tail elevated and nose on the bottom. Thanks for the response

      The koi may have mated before the one koi started laying on the bottom of the pond

      Reply
    • I don’t deal much with catfish but can you tell me if there is anything you can think of that has happened to your pond lately? Has there been any chemicals sprayed near your pond or perhaps heavy rains that may have washed chemicals into your pond?

      Reply
  107. Hi I have a 20,000 litre pond with 3 largish white koi. I have never had any problems and have just noticed that one of the fish has got three bright red spots on his body and his front fins are becoming edged in red. Don’t think this is a colour change , what could it likely be and how to treat.

    The pond is south facing, has a good filtration system, but we have recently had a serious infestation of blanket weed which we treated chemically. Other than that nothing changed. Fish approx 8 years old

    Reply
    • Do the red spots look waxy? Carp Pox is usually to blame for that but if its blood red that may mean internal bacterial infection. If that is the case then something like MediKoi or MedFinn would help as well as increasing salt in the pond.

      -Grant

      Reply
  108. I need help I have a disease or parasite in my koi dam Its eating away at fins eyes heads of my koi I have treated with everything on the market but no success My kois are eaten alive full of holes sores I have 2 filter systems running but eventually put activated charcoal in because maybe somebody poisened my koi with something My battle started in Jan and so far i have lost 107 koi Only since the water we use was municipal water wich had “Chloromite” in

    Reply
    • Its always tough to be sure what is attacking your koi but potassium permanganate or Aquascape Praziquantel are good options for treating your fish if you suspect parasites. You could try increasing the salt first (as high as 0.6%) that helps ease the koi osmotically and also will weaken or kill parasites that can’t handle salt.
      -Grant

      Reply
  109. I have a white koi that is slightly bent but has a large bump on the side, looking like the scales are infected with it being orande around it. Do you have any idea what it could be

    Reply
  110. I have a large orange and black koi fish and he looks like he has white stuff on his back and head. It won’t come close enough to tell if it’s something on him or if he is turning white. What would cause either one of these to happen?

    Reply
  111. Hi where can you buy medicated fish food for bacteria infections. I understand tbe federal government has taken it off the market. Just trying to find some for next summer in case I need it. Any info would be greatly apprrciated, thank you Pat in Ohio

    Reply
    • You can try looking for medi-koi on amazon. It might still be there. As i understand it, you can still get medicated fish food with a prescription.

      Reply
    • Try frozen or cooked peas first. It is used by a lot of koi owners to reduce impaction (which can lead to swim bladder issues).
      Grant

      Reply
  112. i have an outside koi pond in the back yard with about 15-20 koi. A few days ago i saw the maybe 3 or 4 of the fish have no gills, like they have been ripped off or bitten off, but its only a few fish that have this problem. I am not sure what it is from or how to fix the problem or how i can help them. can the heal and grow back the gills? or are they going to look this way the rest of there life. I have had these fish and this pond for about 5 years now, 3 years ago a bird cleaned all my koi fish out and had to start over and got plants with koi eggs on them so these fish are about 3 years old now and i have never had a gill problem like this with any of my fish before , please let me know what i can do asap , cause its October now and winters around the corner and i want to help them and fix this prob before winter is here and before it happens to any other fish. Ikeep a clean clear pond an reg add salt monthly and clean my filters monthly so idk whats causing this. Also i went to check my filter when i saw this gill prob with the fish and when i opened my filter up i saw that it was loaded with these worm like things , almost look like small leeches and on further insp i saw that they are all over my waterfall. Is this related to the gill prob or not. Are these worms something i should worry about or not, and how can i get rid of all thses worms cause im sure they are also in the piping system as well. Anyone can help me out with some good advice I would be grateful!

    Reply
  113. I have a year old koi in a 1200 gallon pond. He had been fine hibernating, since it is about 30 degrees here. The water temperature is 15 degrees. I went out yesterday and thought he had died. Floating sideways on top of the water. I went to get him and he swam around disoriented. I caught him with a net to look more close. He looks like he has cloudy eye but also white fluffy patches on his body. I started treatimg with melafix but should I treat with something else. This morning he is right side up but hiding at the bottom behind a rock.

    Reply
  114. Thank u for this informative site. I have the koi book u have listed and like it. I have a friend who just opened her pond and it’s been about four to five weeks. She has had a consistent high pH issue and was trying to treat because no matter what time of day it was it was always at 9. Today One koi passed . Suddenly started swimming in circles as if it suddenly became blind. WAs thinking dropsy because she stated that the eyes were swollen as well as lips red but not sure- immediately thought edema. I suggested 30 percent water change and add salt. Bring dead fish to store test water and see if they can do a scraping to check for parisites. Any other suggestions or possible causes.

    Reply
  115. Hi there I have lost five fish this spring since. Have done several water changes and have done two rounds of pro form c and 1 round of aquaprazi fish seemed ok but now I have a couple with reddish orange ski colored rash? Don’t know never had anything like this also one tha have a tan looking spots on top of the back towards the tail. Any help with what it could be
    Thanks
    Joe

    Reply
  116. I have a small goldfish koi that has lost fin. There is what appears to be a white sore where the fin was. What could have cause this? How do I treat him?

    Reply
  117. My koi have blood in there fins and tails and down the sides of them. My goldfish and shubunkin are fine. When they die they r full of blood. Only my big koi r sick. The 4 new babies r 3inches and are fine. I’m so confused. I did water exchanges,, extra salt,, extra pump,,melafix and ammonia nitrite. The ph strips look a lot better but I’m still loosing fish. What to do?? Thanks bunches

    Reply
  118. Two of my koi have bubbles attached to them it’s not ich or any of the other disease that I read about has anyone else had this problem

    Reply
  119. Hi there my name is Maranda am a new koi owner and I have more of a question then a comment so please if your willing to read this and help me I would be most appreciative to you cuz god knows I tried everything asked a few pet shop owners and even emailed the pond guy and I got nothing back so maybe you are just the answer to my prayers so with that being said let me give you some background information on my situation and then I will ask you my question. I have a few koi fish along with a couple of goldfish that I brought in the house for the winter and I Seem to run in to a problem and Reading your page I’m confused because my fish is displaying all the signs in every one of those diagnose diseases the most noticeable symptoms in my fish is that they are acting like they have a broken or bent tail, swimming sideways and turning pink where the white should be they also rub themselves on the water lilies pots. when I noticed this strange behavior in the beginning they were swimming in the out going stream of the filter I thought nothing of it just them being silly and cute until I noticed that my white and orange koi was a little pink thats when I started to get concerned then within a day they started swimming sideways and displaying what appears to be a bent tail but all in all they do have a good appetite and I change my water every other day 50% to 90% I do have a filter but I like to make sure the water is clean for them so I change it myself every other day, I just don’t understand what’s going on with them could you help me please I have purchased some medicine called pimafix and melafix and also aquacura prazi-cura do you think these are what I need to cure them? I have already started pimafix and melafix about 3 to 4 days ago and upon reading The description of the aquacura treatment I wanna say it reads better then the other one so my question is if I stop pimafix and melafix treatment before the time required and start the aquacura treatment will that harm my koi and goldfish in anyway? And do I have to clean the whole tank out completely before I start the aquacura treatment or can I just remove the water and add new water with out a total clean out? So now you know my situation and I’ll let you decide if you want to help me or not but I’m hoping you would want to help me. You can email me back at this email that I provided below anytime is a good time for me hope to hear from you soon stay safe and thank you for your time and understanding I appreciate it greatly.
    Maranda Gutierrez

    Reply
  120. Hi
    We inherited a pond with 2 large and appx 20 smaller koi. Weve been trying to read up on how to look after them. However, all of the smaller to medium size koi look unhealthy. It would be pointless quarantining as 90% have either white spot, a greeny coloured substance covering them, several are bloated to one side and one has popeye. We have done a water change, we have a good pump and filter which are clean. Weve vacuumed the debris, now we are stuck! The kou belonged to my parents and I font want to loose them. Any ideas desperately recieved.

    Reply
    • Christine, It may be that there are too many Koi for the size of the pond. If there is a fish or aquarium store nearby, consider getting the water tested. It may show an imbalance, of so… I would focus on the water quality first. Improving the water quality may be enough to get the Koi healthy again. Hope that helps!

      Reply
  121. My Koi and crucian carp have a cloudy shadow down both side looked health feeding well just this shadow on most of fish in pond. I cannot find no reference that matches the complaint
    Many regards
    Paul

    Reply

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