perch, common name for some members of the family Percidae, symmetrical freshwater fishes of N Europe, Asia, and North America. The perch belongs to the large order Perciformes (spiny-finned fishes) and is related to the sunfishes and the sea basses. Best known is the yellow (also called red) perch ( Perca flavescens ), a popular game and food fish abundant in lakes and large streams, where it feeds on insects, crayfish, and small fish and grows to an average length of 1 ft (30 cm) and weight of 1 lb (.5 kg). The voracious walleye, or walleyed pike ( Stizostedion vitreum ), another member of the family, is darker and larger (up to 10 lb/4.5 kg). Very similar to the walleye but slenderer and smaller is the Eastern sauger, or sand pike ( S. canadense ). The native American darters (2–3 in/5–8 cm), found E of the Rockies, are a subfamily containing many species, most of them brilliantly colored. Of separate families are the pirate perch, a chubby little fish of sluggish streams and bayous (family Aphredoderidae), and the trout perch, or sand roller, a small fish abundant in the Great Lakes (family Mugiloididae). Perches are classified in the phylum Chordata, subphylum Vertebrata, class Osteichthyes, order Perciformes, family Percidae.