Quarantine New Additions to Your Fish Pond
Many of us have fish that mean more to us than some family members. It is our job to take care of these fish and make sure they are healthy. This starts from the time we buy new fish. To protect the fish in your pond you should quarantine new additions, regardless of how well you trust your source. Quarantining is recommended but is not a necessity. I would never put at risk prized fish that cost hundreds or thousands of dollars by not quarantining, but if you have a new pond or only a few inexpensive goldfish, you may choose not to quarantine the new fish.
If you have a quarantine tank or pond then you can keep new arrivals away from your other fish and treat them yourself to make sure that they are healthy before introducing them to your other prized fish. A quarantine tank need not be large depending on how many fish you will have in it at any time. A 50 to 100 gallon tank will suffice for goldfish and smaller koi, if you need a tank for larger koi (above 15 inches) then you may want a 200 to 300 gallon tank. There are several ways to obtain a tank without spending a lot of money. Rubber Maid stock tanks are available at some hardware stores and farmers co-ops. These are very durable and will stand up on their own. A rubber pond liner tank has the advantage of being able to be dismantled when not needed. A simple frame of landscape timbers criss-crossed Lincoln log fashion will make a good framework to support the rubber liner. Simply place the liner in the frame and tack a batten strip around the edges to hold the liner in place. This can be placed in a basement, garage or outside in the shade. However you create your quarantine pond, make sure that you know the exact volume of water it will hold to make any treatments accurate.
You will also want to have some leaf netting to place over the top of the tank to keep the fish from jumping out and to protect them from any predators. By floating a piece of styrofoam (such as a lid from a cooler) on the surface, you will provide a less stressful situation for the fish. If doing so, make sure you are not covering all the surface. A small submersible pump will keep the water well oxygenated while the tank is in use. Of course you will want to have your test kits available to make sure that the water quality is always good. A few small fish in a large tank may be fine without any filtration for a few weeks but you should be prepared to do partial water changes if necessary to reduce any ammonia or nitrites, which may accumulate. A good method that will eliminate the need for large water changes is to use an in-pond filter. Your pump will draw water through this filter decreasing the need to clean the pump screen. The filter uses a biological filter medium. This medium can be placed (before using the quarantine tank) in your pond's biofilter or in the pond where water will flow over it to grow a culture of bacteria. This way you have a live biological filter when needed to use in your quarantine tank. If the fish did show health problems during quarantine, remember to sterilize the media before putting back into your pond to grow a new culture of bacteria. This can be done by soaking it in a solution of 10% Bleach - 90% water for at least 24 hours, then rinse well and allow to fully dry. It is possible to have a quarantine tank without circulation and filtration, but it will be necessary to perform daily water changes and monitor the chemistry very closely. If choosing no filtration, you do still need aeration. This can be accomplished with an air pump.
When using your tank as quarantine for new fish, keep the fish on a .3% salt solution to get rid of most parasites. A .3% solution is approximately 2-½ lbs. of non-iodized salt per 100 gallons of water. This salt should be added over a three-day period. Add approximately 1/3 of the salt before introducing the fish, add another 1/3 the next day, and the balance of the salt the day after that. Keep the salt in the water the entire time the fish is kept in quarantine. If you do partial water changes then you will need to add the appropriate amount of salt to bring the solution back up to .3%. Keep new fish in this tank for a least three weeks before adding to your pond. I would also recommend that you use Koizyme in the quarantine tank. These bacteria when added to pond water will reduce the gram-negative bacteria (bad bacteria) from the water lessening the change of spreading a bacterial infection from one fish to another. I also recommend keeping Koizyme in the pond for the same reason. Koizyme will not kill the bacteria that has already infected a fish but it will allow for quicker healing by keeping the bacteria out of the water.
A broad spectrum parasite treatment such as BSDT is a good treatment to use when quarantining fish.
A quarantine tank also makes a great hospital tank when you need to remove a fish for treatment. Some treatments may not be desirable to use in the pond for several reasons. Some treatments may kill the filter or your plants. You can also save a lot of money by treating a small amount of water in a tank as compared with the amount of water in your pond.
A clean quarantine tank can also be used as a nursery when you want to protect baby fish from being eaten by larger fish.
A note on Koi Herpes Virus (KHV): Quarantine is always the best way to reduce the chance of exposing prized fish to any disease. In recent years KHV has spread and become one of the greatest risks facing the koi keeping hobby. Koi can be carriers of KHV and never show symptoms. To help make quarantine more effective for stopping KHV, it is best to have a "test" koi that is in the quarantine tank before adding the new fish. This test fish will be the fish that gets sick if the new koi is a carrier of the virus. Also, make sure that the water temperature is at least 78 degrees to help bring out the KHV symptoms. KHV can NOT be cured and has a mortality rate of close to 100%. At this time, it is believed that KHV does not affect goldfish, although some believe goldfish can still be carriers.