Have you ever wondered how fish survive in cold winter weather, or where they go when lakes and ponds freeze over? Like many people, fish tend to be less active in the cold. As cold-blooded creatures, their metabolism dips when temperatures take a dive.
The layer of ice that forms on top of a lake, pond, river, or stream provides some insulation that helps the waterbody retain its heat. Because warm water sinks, freshwater fish often gather in groups near the bottom. Some species, like koi and gobies, may burrow into soft sediments and go dormant like frogs and other amphibians, but most fish simply school in the deepest pools and take a "winter rest."
In this resting state, fishes' hearts slow down, their needs for food and oxygen decrease, and they move about very little. If you've ever gone ice fishing, you know that a long line, a slow, colorful lure, and a hearty portion of patience are often required to land this quiet quarry! Popular ice-fishing species include walleye, northern pike, yellow perch, and rainbow trout.
Original article: Where do fish go when it freezes outside?