Water flea is a generic term for a number of small aquatic crustacea characterised by their jumping or jerky mode of swimming. Most are between 0.1 mm and 3 mm in length. Most commonly, they will be species of Daphnia but a number of other species are also commonly included, including Cyclops spp., and Diapthomas spp.. Water fleas are commonly sold as aquarium food since they are easy to culture and reproduce rapidly.
