Perch is a common name for freshwater fish from the genus Perca, which belongs to the family Percidae of the large order Perciformes. The name comes from Greek: πέρκη, romanized: perke, meaning the type species of this genus, the European perch.

Perciformes, also called the Acanthopteri, is an order or superorder of ray-finned fish in the clade Percomorpha. Perciformes means "perch-like". Among the well-known members of this group are perch and darters (Percidae), sea bass and groupers (Serranidae).