The Percidae are a family of perciform fish found in fresh and brackish waters of the Northern Hemisphere. The majority are Nearctic, but there are also Palearctic species. The family contains about 200 species in 10 genera. The darters, perches, and their relatives are in this family; well-known species include the walleye, sauger, ruffe, and three species of perch. However, small fish known as darters are also a part of this family.