Wikipedia
Cryptomonas is the name-giving genus of the cryptomonads. It is common in freshwater habitats and often forms blooms in greater depths of lakes, or during winter beneath the ice. The cells are usually brownish in color, and have a slit-like furrow at the anterior. They are not known to produce any toxins and are used to feed small zooplankton, which is the food source for small fish in fish farming. In fact, the zooplankton, Ceriodaphnia quadrangula, feeds specifically on Cryptomonas erosa and nothing else. Many species of Crytomonas can only be identified by their molecular signatures. Cryptomonas can be found in several marine ecosystems in Australia.
Cryptomonas is a dimorphic genus, meaning it could be either protozoan (Cryptomondida) or alga (Cryptophyceae). Currently there are 26 species of Cryptomonas.