overwintering fish indoors
Although many experts agree that the best place for most pond keepers to over winter their fish is in the pond itself, there are many cases where over wintering fish indoors is the best or sometimes only option. If your pond is less than 30” deep or you don’t feel comfortable leaving your fish outside follow these guidelines to keeping them indoors.
Tank
Choose a holding tank large enough that your fish aren’t crowded and have plenty of room to swim freely. Round tanks are better than square, as fish tend to bump their noses in square corners. Tanks with bottom drains ease the job of water changes greatly.
Pump & Filter
You will still need to filter the water 24 hours a day, just like in your pond. If you have a system outside that is easily movable, bring it in and use that. This way the filter is already colonized with the nitrifying bacteria needed. If not, there are several small pump and filter systems to choose from.
Water
If possible, pump water from your outside pond into your holding tank, fill the tank with that water and refill your pond with tap water. If tap water is used to fill your holding tank, be sure to dechlorinate and to add stress coat, Nite-Out II bacteria, and pond salt to .3%.
Water Conditioners
Water should be dechlorinated whenever added. The salt level should be kept at .3% and stress coat should be added every two weeks or every water change.
Cover
Fish (especially koi) tend to jump when moved into holding tanks. Netting should be stretched across the top of the tank and removed only when necessary.
Feeding
If the water temperature is above 55 degrees F, the fish will need to eat. A reduced protein, spring and autumn blend is ideal. How often you feed also depends on water temperature. Below 68 degrees F, a couple times per week is plenty. If it’s above 68 degrees F, you should feed every other day. But keep in mind the more you feed the more ammonia is produced, shortening the length of time between necessary water changes.
Light
If you are feeding your fish they will remain active. They need light at least part of the day. Full spectrum or plant growing lights are best.
Testing Water/Water Changes
If you have a good filter that had time to build up bacteria, it should be able to keep up with ammonia and nitrites produced by the fish. Without plants, there is nothing to get rid of nitrates produced through the biological activity that takes place in the filter.
Nitrates are non-toxic in low levels but as levels rise they can cause health problems to your fish. Therefore water changes will be necessary. How often you test the water will depend on the number of fish and size of the system. Test for ammonia, nitrite and nitrate every few days until you know the system is working, then test at least bi-weekly after that. If results are high in any of the tests, do ½ to 2/3 water change immediately. Be sure to dechlorinate and add stress coat according to the number of gallons you have added. Once full, test the salt level and add accordingly.