Freshwater fish - species, habits, habitat

The water area of our planet is inhabited by about 20,000 different species of fish. Approximately one-tenth of them refers to commercial. In addition to food, commercial fish provide us with medicines, industrial raw materials, technical fats, fertilizers, pet food. Fish fishes are divided into freshwater, through-water and marine.

Freshwater fish, whose share in the world catch is about 11%, lives in rivers, lakes and ponds. The largest commercial value is of catfish, carp and percid fish.

The largest fish that live in the rivers are the Amur kaluga (representative of the sturgeon family), whose weight can reach 1000 kg, and the length of 5 m, Chinese psephurus (length up to 7 m), European catfish, growing to 5 m in length and over 300 Kg weight, South American arapaim (200 kg weight, more than 4.5 m in length). But such giants are rare. Most freshwater fish that live in domestic water bodies are of average size.

Freshwater fish for commercial purposes is partially bred in special artificial ponds - for example, trout, carp, tilapia, cupid, carp. Of the people living in rivers and lakes, the pike, catfish, carp, crucian carp, bream, perch, roach are most important for catching.

In natural reservoirs, freshwater fish live mainly near the coast, where there is plenty of food and convenient places for spawning. In the summer in shallow water you can always see flocks of fry. The nearest zone is inhabited by fish, not too demanding for water quality, i.e., its purity and oxygen content. This is a pike, crucian, tench, roach. A little further live perch, bream, ide. Catfish, pike perch and salmon choose the most remote and clean places.

Such species of river fish as trout, char, and plucking are found in brooks. In small lakes there are mainly pike, roach, ruff and loach. Large lakes in terms of the number of species are not inferior to sea water. The number of fish species there exceeds several dozen.

The oxygen content in water is the most important factor affecting the diversity of its inhabitants. In poorly oxygenated water bodies, only the most unpretentious fish are found, since in summer heat and in severe cold many of their species die out from suffocation. Lines and carp can exist in oxygen-poor small ponds, which are frozen through in winter. Ruffs well tolerate oxygen hunger, but require clean running water.

The most demanding of high oxygen content are salmon, pike perch, and sturgeon.

Freshwater fish also responds to temperature fluctuations. Some of its species are unable to exist at a temperature below a certain one. So, for fish of the carp family this figure is + 10 ° С. There are fish that do not tolerate high temperatures (whitefish, burbot, palia). In the heat, they hide under the rocks and crawl out only with the onset of cold weather. Other fish can perfectly exist in cold water and survive even in freezing ponds. In the freezing winter, certain fish species can fall into an anabiotic state.

Freshwater fish, in addition, is sensitive to sunlight. There are also lovers of lighted and dark ponds. Lamprey prefers darkness, and roach, for example, gathers in sunny, well-lit places. Fry of salmon from bright light is taken in the stones.

Experienced fishermen can determine what kind of fish flashed in the water depth, not only in appearance, but even in a characteristic splash, because each of them moves in its own way.

Fishing in our country is a favorite national holiday, which includes elements of competition, sports excitement, communication, adrenaline rush, fresh air and the practical side of the matter in the form of a legitimate catch. Today, there is a practice of breeding fish in special ponds with the subsequent sale of licenses to visit and capture fish in them.