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 , meaning the type species of this genus, the European perch ( P. fluviatilis).
Many species of freshwater game fish more or less resemble perch, but belong to different genera. In fact, the exclusively saltwater-dwelling red drum (which belongs to a different order Acanthuriformes) is often referred to as a "red perch", though by definition perch are freshwater species. 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.
Species
Most authorities recognize three species within the perch genus:
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The European perch ( P. fluviatilis) is primarily found in Europe, but a few can also be found in South Africa, and even as far east on the Southern hemisphere as Australia.
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The Balkhash perch ( P. schrenkii) is found in Kazakhstan, (in Lake Balkhash and Lake Alakol), Uzbekistan, and China. It has a dark gray/black color on its dorsal side, but the ventral areas of the fish are a lighter silver or even sometimes green color. The Balkhash perch also displays the vertical bars on its sides, similar to the European and yellow perches. In the latter half of the 20th century, the Balkhash perch was introduced into the basins of the Nuru River and Chu rivers. The introduction of these fishes to the Nuru and Chu rivers was successful. Because of this success, the population of Balkhash perch in the Balkhash Lake is rarer now. They are similar in size to the yellow and European perches, weighing around .
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The yellow perch ( P. flavescens), smaller and paler than the European perch (but otherwise nearly identical), is found in North America. In northern areas, it is sometimes referred to as the lake perch. This species is prized for its food quality and has often been raised in hatcheries and introduced into areas in which it is not native. These fish typically only reach a size of about and .
Anatomy
External anatomy
Perch have a long and round body shape which allows for fast swimming in the water. True perch have "rough" or
ctenoid scales. Perch have paired
Pectoral fin and
, and two
, the first one spiny and the second soft. These two fins can be separate or joined.
The head consists of the
skull (formed from loosely connected bones),
,
mouth, operculum,
, and a pair of
(which has no connection to the oral cavity). They have small brush-like teeth across their
and on the roof of their mouth. The gills are located under the operculum on both sides of the head and are used to extract oxygen molecules from water and expel carbon dioxide; the gills have
inside the mouth.
External anatomy can be used to determine the sex of perch in multiple ways. Perch have two posterior openings located on their abdomen, the Anus and urogenital. In males, the shape of the urogenital opening is round and larger than the anal opening. In females, the urogenital opening is often a V- or U-shape which is a similar size to the anal opening. Also, males usually have a more brown-red colored urogenital opening compared to females.
Internal anatomy
The
esophagus is a flexible tube that goes from the mouth to the stomach. The
stomach is connected to the intestine via the pyloric sphincter.
The
intestines of perch consist of the
small intestine and
large intestine; the intestines have many
Pyloric caecae and a
Spiral valve, the small intestine consists of a part called the
duodenum. The
spleen is located after the stomach and before the spiral value. The spleen is connected to the circulatory system, not part of the
digestive tract. The
liver is composed of three lobes: one small lobe (includes the gall bladder) and two large lobes. Perch have long and narrow
that contain clusters of
which empty into the
mesonephric duct.
They have a two-chambered
heart consisting of four compartments: the
Sinus venosus, one atrium, one ventricle, and conus.
Perch have a
swim bladder that helps control
buoyancy or floating within the water, the swim bladder is only found in bony fish. In perch, the duct connecting the swim bladder to the
pharynx is closed so air is unable to pass through from the mouth, these fish are called
Physoclistic. Specifically in perch, the gas bladder can vary from 12% to 25% of
oxygen and 1.4% to 2.9% of
carbon dioxide gas.
Perch reproductive organs include either a pair of
testes (sperm-producing) or a pair of
Ovary (egg-producing).
Habitats
Perch are classified as
, choosing waters where smaller fish,
shellfish, zooplankton, and insect
are abundant.
The yellow perch can be found in the central parts of the United States in freshwater ponds, lakes, streams, or rivers. These fish can be found in freshwater all over the world, and are known to inhabit the
Great Lakes region, in particular
Lake Erie. These fish inhabit bodies of water where vegetation and debris is readily accessible.
In the spring when the perch chooses to spawn, they use vegetation to conceal their eggs from predators.
Fishing
Perch are a popular
gamefish species. They are known to put up a fight, and to be good for eating. They can be caught with a variety of methods, including
Fishing float fishing, lure fishing, and
Bottom fishing. Fly fishing for perch using patterns that imitate small fry or invertebrates can be successful. The record weight for this fish in Britain is , the Netherlands ,
and in America . The biggest recorded catch in Sweden is 3.15 kg (6lb 15oz) in 1985.
Perch grow to around and or more, but the most common size caught are around and or less and anything over and is considered a prize catch.
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