Others eat detritus that has sunk to the bottom. Not all organisms are easily classified as planktonic or benthic. The best known group of aquatic consumers is fish. Many small fish, such as sunfish and perch, primarily eat zooplankton. Walleyes, on the other hand, spawn on a gravel bottom.
Lake trout live only in very clear lakes with cold, well-oxygenated deep water.
In contrast, carp are adapted to warm turbid, low oxygen lakes with mucky, high organic matter bottoms. View images of fish, Figure 21 . Methane gas causes the bubbles you may have observed in lake ice. The bottom, and most dense layer of a stratified lake. It is typically the coldest layer in the summer and warmest in the winter.