Channel catfish (amiurus nebulesus)
The Belarusian name - amerykanski somik; local - dwarfish somik, are more rare Californian somik, a cat. Treats fishes of family of cats catfishes (Ictaluridae) of group of somoobrazny (Siluriformes).
Radical habitat of channel catfish are fresh waters of North America, from area of the Great Lakes to Florida. It is artificially divorced in the rivers of the Pacific coast. In 1885 it is delivered to Europe, for cultivation in aquariums in the beginning, and then it was let out also in natural reservoirs. In limits of the western areas of Ukraine and Belarus it is delivered in 1935 from Germany and till this moment meets in lakes of the Volynsk and Brest regions, is object of local trade. In Belarus lives in lakes Oltushsk, Orekhovsk and Lukovsk (the basin of the Western Bug), Small, Anonymous and Karasinsky (the basin of Pripyat). In basins of other rivers there is no channel catfish.
Coloring of a body from yellow to dark brown and even black, a belly light, whitish, sometimes spotty. Intensity of coloring changes depending on habitat conditions. Length of an intestinal path 3,2-4,0 times exceeds body length. Differs from ordinary som in the small sizes, existence of a fatty fin, longer back and short anal in fins, existence of 4 couples of short moustaches (at som ordinary 3 couples of short moustaches).
In new conditions of dwelling the way of life of channel catfish is studied poorly. It is known that it is unpretentious to dwelling conditions, well got accustomed in our lakes, it is capable to master very intensively natural food supply of reservoirs and to accumulate high number. It is most active in summer months, but already with occurrence of the first cold weather gets into deep holes and lies there for all winter. Leaves places of wintering only after opening of reservoirs.
Becomes polovozrely in 4 years. Spawning in the lakes of Belarus happens at the end of May - the beginning of June, at water temperature about 18-20 °C. Ikrometaniye single, caviar of quite large, about 3-4 mm in the diameter, is imprisoned in a mucous membrane.
According to literary data, the sizes of a somik reach 45 cm of length and the weight of 2 kg. In reservoirs of Belarus the largest sizes in ulova made 30,6 cm and 484 g, the main part is caught weighing less than 100 g. Growth rate is quite low, linear prirosta in the first year make about 6-8 cm, in the second - about 5 cm, and then sharply falls to 2-3 cm a year. Weight to three-year age hardly reaches 40-50 g, in five-year-old exceeds 100 g a little and only in seven-year-old reaches 300 g.
As food of channel catfish serve the most various animal organisms, mainly larvae hironomid, caddis flies and dragonflies, water burros, small molyolyusk. Is a strong contender on food with the main trade species of fish, in particular with the bream, destroys a large number of his calves and thresh.