Have you ever wondered how the fish in your pond or lake cope with cold winter weather? While fish have to deal with low water temperatures, less food and lower oxygen levels, there is still some activity under the surface of the water.
Fish are cold-blooded animals which means that their body temperature is about the same as their surroundings. As a result, their metabolism slows down in colder weather. Since they are less active, fish can survive longer with reduced amounts of food and oxygen. When temp
eratures drop, many fish move to the bottom of lakes and ponds where the water is warmer. Some go into diapause, a state with extremely slow heart rate.
Even though fish are less active, they still require some oxygen. As winter progresses, dissolved oxygen levels can drop too low for some fish to survive which may result in a winterkill. Low oxygen can occur when ice-covered lakes and ponds are blanketed with snow which prevents sunlight from reaching the aquatic plants in the water. The plants cannot carry on photosynthesis, and as they begin to die and decay, the bacteria that decompose the plants consume more oxygen.
Here are some steps you can take to prevent winterkill in your
pond or lake.
|Bluegill: Eric Enbertson, Division of Public Affairs, cropped from U.S. Fish and Wildlife Service Image
- Install an aeration system to keep a portion of the pond free from ice. This will allow oxygen from the air to mix with the open water.
- Gradually stop feeding your fish when winter is near. Completely stop feeding once the temperature reaches 40-45 degrees. Since fish are less active, they require less food.
- Remove snow cover from the ice in order to allow light to get to aquatic plants. However, making holes in the ices will not help.
KDSWCD sells fish for pond stocking in the spring and fall. Orders are now being taken for the spring fish sale. Fish will be distributed at the district
on April 16. For order form and information on the sale visit