Autumn River Crab Farming: Beware of Preventing River Crab Death

Autumn is the season when river crabs mature and are harvested, and it is also the peak period for river crab deaths. Therefore, strengthening autumn farming management of river crabs is the key to preventing autumn deaths of river crabs and improving river crab farming profitability.

Preventing natural death. As the saying goes: “When the west wind blows, crab legs itch.” Every year from September to November, a batch of river crabs that have grown for 2 years molt from yellow crabs into green crabs, their gonads mature, and they enter the final stage of their lives. Any river crab whose legs itch and wants to escape has already matured, and its internal osmotic pressure rises, making it unable to adapt to the low-osmotic-pressure freshwater environment, which leads to the natural death of most river crabs. Therefore, these river crabs should be caught and sold in a timely manner.

Preventing death from cold. In autumn, the temperature difference between day and night is large, and the water temperature difference is also large, sometimes reaching as high as 10°C. River crabs die because they cannot adapt to these environmental conditions. Therefore, prevention must be taken. Prevention methods: 1. Usually pay attention to adjusting the water level and controlling drastic changes in water temperature; the temperature difference between newly added water and old water should not exceed 3°C. 2. Keep more cover on the water surface such as water hyacinth and alligator weed, but it should not exceed 1/2 of the water surface. 3. When the weather changes, deepen the water level.

Preventing death from indigestion. In autumn, due to drastic changes in air pressure and water temperature, the feeding habits of river crabs change, which easily causes indigestion, and in severe cases can even lead to the death of all river crabs. Therefore, careful prevention and treatment are necessary. Methods: 1. Improve water quality and regularly disinfect with limewater. 2. Regularly add antibiotics and growth hormones to the feed. 3. Do not feed or feed less plant-based feed, and increase animal-based feed, especially high-protein feed such as earthworms and river snails. 4. Feeding should be done at fixed times and in fixed amounts, and when the water temperature drops, the feeding amount should be appropriately reduced.