Healthy lakes need algae. Algae are important to the productivity of a lake or water body. Algae are primary producers. They use sunlight (through photosynthesis) to produce carbohydrates and are eaten by grazers such as protozoa and zooplankton (little animals like water fleas and rotifers). The zooplankton are, in turn, grazed upon by fish, which are eaten by bigger fish, and on up the food chain. A productive lake produces large fish and good fishing for humans as well as supporting food and habitat for wildlife and waterfowl. In this context most algae are desirable for lakes.