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 fishes known as darters are also a part of this family.This family is characterized by a greater or lesser degree of armour about the head, caused by the presence of teeth or spines on the cheeks and opercles (gill covers) or their edges, and by two narrow bands of numerous close-set teeth on the sides (palatines). Also, many percid fishes have a heart-shaped plate of teeth on the roof of the mouth (vomer). The shape of these fishes is usually somewhat oblong and laterally compressed. Their scales are generally harsh and rough to the feel, or ciliate. Percid fishes are among the most beautiful of the freshwater fishes due to their brilliant colors (red, brown, orange, and yellow are the most predominant tints).