For the unit of measurement, see pole.

Perca flavescens (Yellow perch)
Perca fluviatilis (European perch)
Perca schrenkii (Balkhash perch)
A perch is a freshwater bony fish belonging to the family Percidae. Perch, of which there are three species, lend their name to the largest order of vertebrates: the Perciformes, from the Greek perke meaning perch, and the Latin forma meaning shape. All perciform fish share the perch's general morphology.

The European perch (Perca fluviatilis) is found in Europe and northern Asia. It is 15-60 cm long, and may weigh up to 10.4 kg. It is usually dark green with red fins. It has been successfully introduced in New Zealand and Australia where it is called redfin perch.

The Balkhash perch (Perca schrenkii) is found in Kazakhstan; in Lake Balkhash and Lake Alakol . It is very similar to the European perch, and grows to a comparable size.

In the United States and Canada there is the smaller (10-25 cm long, 1.4-4.5 kg in weight) and wider-mouthed species, the yellow perch (Perca flavescens). It is paler and yellowish and its fins are not as red; although recognized as a distinct species[1], the yellow perch may be a subspecies of the European perch (in which case its binomial name would be Perca fluviatilis flavescens). This view is supported by successful cross-breeding of the two species, which has generated faster growing offspring[2]. However, this may be an example of interspecies hybrid vigor and it is unclear whether or not these hybrids are viable.

Perch have ctenoid scales . When looking through a microscope, the scale look like a plate with growth rings and spikes on the top edges. Externally the anatomy of perch is simple enough. On the dorsal side of the fish, there consists a upper maxilla and lower mandible for the mouth, a pair of nostrils, and two lidless eyes. On the posterior sides are the operculum, which are used to 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. On the anterior end of the fish, there are two dorsal fins. The first one is spiny and the second is soft. There is also a caudal fin and anal fin. Also there is a cloacal opening right behind the anal fin.

The perch spawns at the end of April or beginning of May, depositing it upon weeds, or the branches of trees or shrubs that have become immersed in the water; it does not come into condition again until July.

The best time for fishing for perch is from September to February; it haunts the neighborhood of heavy deep eddies, camp sheathings, beds of weeds, with sharp streams near, and trees or bushes growing in or overhanging the water. The baits for perch are, minnows, red, marsh, brandling or lob worms and shrimps. The tackle should be fine but strong, as with a fish bait a trout or pike may frequently be hooked. Perch, unlike fish of prey, are gregarious, and in the winter months, when the frosts and floods have destroyed and carried away the beds of weeds, congregate together in the pools and eddies, and are then to be angled for with greatest success from 10 to 4 o'clock, at the edge of the streams forming such eddies.

References

• Gilberson, Lance , Zoology Lab Manual 4th edition. Primis Custom Publishing . 1999.