Gymnocephalus

Gymnocephalus is a genus of perches native to Western Eurasia. They are collectively called ruffes and resemble the common perches (Perca), but are usually smaller and have a different pattern. There are currently five recognized species in this genus: In Europe they are found in the Caspian, Black, Baltic and North Sea basins; in Asia in the Aral Sea basin and the Arctic Ocean basin eastward to Kolyma drainage.