The cause of death of river crab in autumn

Die of a cold

In autumn, the temperature difference between day and night is large, sometimes up to about 10 ℃, river crabs are difficult to adapt, it will cause colds, resulting in loss of appetite, difficulty breathing and death. Preventive measures: usually, we should pay attention to adjust the water level, control the drastic changes of water temperature, the temperature difference when injecting new water should not be more than 3 ℃, and plant more cover plants such as water hyacinth and water peanuts on the water surface (not more than 1 inch 2 on the surface). When the weather changes, the water level should be deepened appropriately.

Dyspepsia

Due to changes in air pressure and water temperature, it is easy to cause indigestion and death of river crabs. Prevention and control methods: first, to change the water quality, regularly disinfect with lime water; second, to add antibiotics and auxins regularly to the food; third, not to feed plant bait or less to increase animal bait, especially high-protein bait such as earthworms and field snails; fourth, feeding should be fixed and quantitative, and the amount of bait should be appropriately reduced when the water temperature drops.

Die of natural causes

As the saying goes, "when the autumn wind blows, the crab's feet itch." From September to November every year, a group of river crabs growing for 2 years have shelled from "yellow crabs" to "green crabs" and entered the final stage of life. Because this kind of river crab has been sexually mature, the osmotic pressure in the body is increased, can not adapt to the freshwater low osmotic pressure environment, and often die naturally. Farmers should catch and sell these river crabs in time so as not to affect their income.