The water temperature for breeding hairy crabs is 20-25 degrees. Eriocheir sinensis is a temperature-changing animal, and its body temperature changes with the water temperature, which is generally only 0. 1℃. When the water temperature changes sharply, the river crab will produce stress reaction and be prone to diseases. When the water temperature changes suddenly, the crab muscles relax, the appendage joints become soft, the movement is weak, and even muscle necrosis occurs. When adding fresh water, if the temperature difference exceeds 3℃, the river crab is prone to catch a cold and die; In the hot season, if the water temperature below 50 cm exceeds 28℃ for a long time, the river crab is prone to precocious puberty; When the water temperature is lower than 10℃, river crabs will burrow or drill mud for the winter, which will affect fishing.