Perca fluviatilis

Perch is a common name for fish of the genus Perca, freshwater gamefish belonging to the family Percidae. The perch, of which there are three species in different geographical areas, lend their name to a large order of vertebrates: the Perciformes, from the Greek perke meaning spotted, and the Latin forma meaning shape. Many species of freshwater gamefish more or less resemble perch, but belong to a different genera. In fact, the exclusively salt water dwelling red drum is often referred to as a red perch, even though by definition perch are freshwater fish. Though many fish are referred to as perch as a common name, to be considered a true perch the fish must be of the family Percidae.

The general body type of a perch includes a somewhat long, rounded stature. True perch have "rough" or ctenoid scales. On the anterior side of the head are the maxilla and lower mandible for the mouth, a pair of nostrils, and two lidless eyes. On the posterior sides are the opercula, which protect the gills. Also there is the lateral line system which is sensitive to vibrations in the water. They have a pair of pectoral and pelvic fins. There are two dorsal fins, the first one spiny and the second soft. These two fins can be separate or joined. There is also an anal fin, which is also considered spiny, and a caudal fin. The cloaca lies directly behind the anal fin. All perciform fish share this general morphology.