Daphnia
From Microcosm Aquarium Explorer
Daphnia pulex, the water flea, greatly enlarged. Paul Herbert/Creative Commons
Family: Daphniidae
Species in Genus Daphnia:
none
Daphnia is a genus of tiny freshwater aquatic crustaceans found in lakes, streams, and ponds. They have a jerky swimming motion and small size (.2 to 5 mm), earning them the common name "water fleas."
Live Daphnia are eaten with relish by aquarium fishes, but their nutritional value is rather modest, as a considerable percentage of their body mass is a chitinous exoskeleton. This serves the purpose of providing fiber to the fish and stimulating healthy digestion.
Daphnia is available live, frozen, and freeze-dried.
Many species exist, with Daphnia pulex and Daphnia magna.