Anyone that has cared for or owned koi for any significant period of time has had to isolate their fish for one reason or another. Sometimes its necessary to remove your fish in order to clean their pond or perhaps there are signs of disease that you want to prevent the further spread of -whatever the reason, having a quarantine tank is a necessary component of your koi pond “system”. Quarantine is a great way to isolate your fish in times of stress or times when you want to control which breeding pairs you want to match up. Of course, one of the main reasons for having a quarantine tank is for situations where you suspect your fish is diseased but one thing some koi owners neglect is using it for newly arrived, healthy-looking fish.
Types of Quarantine Tanks
For some, a smaller glass-style aquarium quarantine tank is all that is required when koi are small. Later, when your koi grow too large for glass aquaria a commonly used container is the fiberglass or Rubbermaid tub style. These are nice due to their cost, low weight and versatility. The fiberglass and Rubbermaid tubs can be found at many different retailers but probably the most convenient source will be farm supply and feed stores. If they don’t have the size you need they can find it and order it for you.
Must have’s for your Quarantine Tank
One of the biggest questions that koi pond owners will have when considering setting up a quarantine tank is: “how big does it need to be”? To answer that you first need to consider how large your fish are currently and obviously how large they are going to be. It’s always convenient to plan ahead for when your fish get to be older and larger (which is when you are really going to want to make sure the quarantine tank does its job). As a rule of thumb if your fish are in the 10-11″ (3.9-4.3cm) range look for a quarantine tank that is at least 200 gallons (757 liters). Your quarantine tank needs to have biological filtration. There are some pond owners that don’t think about this because they often don’t keep their fish in quarantine for long enough so they may only have aeration. To do it right the quarantine period should be at least 3 weeks but a full month is better. As mentioned, having plenty of aeration is critical to keeping your fish happy during the quarantine period. In addition to aeration you will want to keep the tank out of direct sunlight. As is the case with your main pond, you provide means for shade via tree canopy or aquatic plants so your quarantine needs to have shade as well. Lastly, it’s important that you effectively prevent your fish from getting spooked and jumping out. This is done with a simple framed screen that fits over the top of your tank. Not only will it keep fish from jumping out but it will keep predators like raccoons and herons from preying on your recovering fish. Another thing that is nice to provide for your fish is something to hide in or near in your quarantine tank like a large PVC pipe or something similar.
Transferring and Maintaining Koi
Whenever you bring a new fish home from a breeder or need to transfer a fish from your main pond to the quarantine tank it’s critical that you ensure the fish has adjusted to the new water temperature (and this is especially true when going from warmer to colder water). A lot of times small koi that you buy will be in clear bags so simply placing the bag on the surface of the tank and allowing the water inside the bag to match that of the tank will suffice. However you choose to make the adjustment be sure it’s gradual -you don’t want to do more harm to a sick fish you are trying to save.
Once the fish has been transferred you will want to wait at least a day before attempting to feed your fish. Oftentimes because of the stress of moving fish won’t eat for a day or two anyway.
How long should you maintain and treat your koi in quarantine?
The treatment, depending on what it is, may actually only be one day but that doesn’t mean your fish is ready to go back to the main pond. You will want to ensure that the fish is good to go and is not showing any signs of the malady so it is recommended that you keep your fish in quarantine for 3 to 4 weeks. A mistake that is often made by koi owners is taking a recently purchased fish and putting it straight into the pond. Though it may look healthy it may also have some healthy parasites that would love to have access to a big pond full of unsuspecting koi. It’s always a good idea to quarantine anything new for 3-4 weeks and watch for signs of disease or parasites (and periods longer than 4 weeks are not unheard of for certain kinds of parasitic infestations).
Creating the Right Conditions
Something a lot of pond owners will do for newly purchased fish that in quarantine is to maintain a raised salinity level to offer osmostic relief to the fish and deal with certain parasites that may be present. For these purposes a level of 2-3 pounds of salt per 100 gallons is a good level to maintain. You will also want to do regular water changes as well. If you are able to tend to the quarantine tank on a regular basis a 10% change out every other day is recommended but if once a week is all you can do then a 25-30% change out should suffice. Doing water changes will give you a chance to vacuum out any uneaten food or feces that may have accumulated on the bottom. For recovering fish a temperature of around 76-77 degrees F is recommended which may call for a submersible heater to be used -a 250 to 300 watt heater should do the trick. And finally, as with your main pond, water quality needs to be monitored and tested regularly.