But swimming in a body of water having a partial covering of ice and at barely above 32 degrees would make short work of the swimmer. Fish, on the other hand have a metabolism controlled by the water temperature, and if their pool is deep enough can stay below at temperatures above freezing. You can spot just one peeking out from under the bridge above.
It was funny because I had my friend look at my post of his fish pond and the photo above. I said, “Look, there is a fish in my picture.” His remark was, “Is it floating.” I guess he was thinking the worse.
They may be moving slow, but hearing me approach, the fish didn’t want to miss a meal.
During winter, fish do not require much protein and any excess is excreted in the form of ammonia. Since the beneficial bacteria are inactive at this time, they can not control the ammonia like they can in the summer. Ammonia can build up in the pond to dangerous levels. So knowledgeable fish owners, like my friend, reduce feeding and then stop when temperatures drop below 45 degrees Fahrenheit.
If the fish remain in the pond for the winter, the pond has to be deep enough to keep them from becoming frozen fish fillets. This pond above is 36 inches deep. There are recommendations for deeper ponds in colder climates.
The pond above has the pump going all year, causing water movement and oxygenation. It also has a small portable heater keeping the ice at bay.
The Koi have been in the pond for maybe a hair over ten years. So these are youngsters in Koi years. They have been recorded living over a hundred years. I myself have a pet like that. My cockatoo is over thirty years that I know of, and can also live to one hundred. He was wild caught, so I am sure he is much older. These are pets you make a lifetime commitment to.
The flagstone bridge is for feeding, pedestrian travel, and a safe place to hide from herons and raccoons for the fish. This is the opposite side view of the first image above with the snow-covered bridge.
This is Big Daddy (not his real name); a monster sized yellow Koi.