A perch is an old unit of length equal to 5.5 yards, also called a rod or a pole.
A perch is a type of fish belonging to the family Percidae, class Osteichthyes.Osteichthyes' common name is bony fish which have over 25,000 species living in marine, brackish and freshwater environments.
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. Two lidless eyes. On the posterior sides are the operculum, which are used to protect the gills. Also their 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.
References
Gilberson, Lance, Zoology Lab Manual 4th edition. Primis Custom Publishing. 1999The 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.