The living habits of Blackfish

Black fish is a common name of snakehead, also known as black mullet, black clam, etc., is a fierce carnivorous fish, its meat is tender, delicious, with high nutritional and medicinal value, strong adaptability, tolerance to hypoxia, easy breeding, fast growth, strong fecundity and less diseases. therefore, it is very popular in domestic and foreign markets, and it is one of the promising freshwater culture varieties.

Black fish like to live in lakes, reservoirs, rivers, ditches and ponds with lush aquatic plants and soft mud, usually lurking at the bottom, feeding or lack of oxygen in the water before moving to the upper and middle layers of the water. Black fish have strong adaptability to bad water quality, water temperature and hypoxia. In addition to the Gill, the respiratory organ of the black fish also has an auxiliary respiratory organ (suprabranchial organ). When there is a lack of oxygen in the water, it can put its head out of the water to breathe the oxygen in the air directly, and is good at jumping. In the case of shock, water injection and bait, often jump 0.5-1.0 meters out of the water.

The survival water temperature of black fish is 0-38 ℃, and the optimum water temperature is 16-30 ℃. When the water temperature rises above 8 ℃ in spring, the black fish often moves in the middle and upper layers of the water; when the water temperature drops below 6 ℃ in autumn, it swims slowly and often lurks in the depths of the water; when the water temperature is too low in winter, it hides at the bottom of the water.

Black fish is a carnivorous fish, and its food varies with the size of the fish. Juvenile fish less than 3 cm feed on chiropods, cladocera and chironomid larvae, while small fish with a body length of 3-8 cm mainly feed on aquatic insect larvae, fly maggots, small fish, shrimp and small tadpoles. Adult fish of more than 20 cm mainly eat carnivorous animals such as small wild miscellaneous fish, shrimp, frogs and so on. When black fish hunt, they do not chase, but hide near aquatic plants or other hidden objects, keep a close eye on the movement around them, and quickly attack and eat their prey when they see fish, shrimp, frogs, etc., passing by.

The growth rate of black fish depends on the quality of the growth environment and the amount of food. Under natural conditions, the body length and weight of 1 winter-aged fish can reach 19-39 cm and 100-750g, and that of 2 winter-aged fish can reach 38-45 cm and 600-1400 g respectively. Under the condition of artificial feeding, the body weight can reach 250 grams in that year and 0.5 kilograms in the next year.

The age of sexual maturity of black fish is 2 winter years old, the individual length is more than 30 cm and the weight is more than 0.5 kg. The number of eggs with a body length of 50 cm is 35000, that of 40 cm is 20 000, and that of 30 cm is about 10 000. Generally, the number of eggs per kilogram is 10, 100, 000 eggs, which is divided into multiple spawning shapes. The spawning season is from April to May in South China and May to July in North China. The breeding water temperature of black fish is 18-30 ℃, and the optimum temperature is 23-28 ℃. Natural spawning is mostly carried out on the banks of still water with lush aquatic plants. Before spawning, female and male parent fish together pick up aquatic plants or plant fragments to build round fish nests. It is about 50 cm in diameter and floats on the water. After the nest is built, before the calm dawn, female and male fish chase each other, estrus, and finally lay eggs on the nest. After spawning, the parent fish lurks at the bottom of the nest and protects the eggs until the seedlings grow to 4-5 cm.