Winter is a stressful time for koi owners. The pond is “closed down” for the season, feeding has stopped and the koi are dormant.
Preparing your koi for winter – Every pond will cool down and warm up at a different rate and that’s why you should have a pond thermometer. Start feeding your koi a wheat germ in early fall as the temperature drops as it will help them to clear their digestive system for the winter. Once your pond water reaches 55 degrees, feeding of the koi should stop completely (There is plenty of food for them to eat on the sides and bottom of your pond.)
As the water continues to cool, the koi go into a dormant phase. Dormancy is when a koi run on a low metabolic rate so when they are in cold water they have a low energy need. During this time they live off of their stored fat.
On warm days do not be tempted to feed your fish because they are showing some activity. Their bodies are still running at a low metabolic rate and they are unable to digest any food they would eat. Turn and walk away – “stop looking at their pathetic faces” – they cannot digest food.
“Closing” your pond down for the winter - There are many preferences when it comes to shutting the pond down completely for the winter or to let it stay running. It really comes down to the individual pond. If you have plumbing exposed to freezing, the best thing is to shut the filter down and empty the pipes. If your pipes are frost proof, then it is possible to keep the pond circulating through the winter.
If you have a waterfall, running the water over the fall can chill the water further as it enters into the pond. Also, ice build up on the fall can cause diversion of the water as it flows down the over the side and possibly drain the pond. If you really believe it to be in your best interest to keep your pond running, the best option is to bypass the waterfall for the winter and have the water enter the pond just above the surface to agitate the surface of the water. This will help keep the surface of the pond from freezing.
The proper size aerator is a must and that’s why it’s so important to know the size of your pond and your fish load. Too much oxygen is just as bad as none. Consider a pond heater or floating de-icer if you have a shallow pond. Remember, it’s necessary to keep an opening in the surface to release toxic gases and provide oxygen (do not hammer or drill the ice if necessary – add hot water to melt a hole.
Most importantly, the best way to ensure your koi come out of the winter season healthy is to have them in good health; good body weight and parasite free.