In the summer, the weather becomes hot, and water temperatures rise significantly. To ensure that river crabs can safely cross the river and increase their survival rate, several key measures must be implemented:
First, it's essential to provide sufficient aquatic vegetation in the crab ponds. Planting species like water hyacinth, duckweed, reeds, and other floating plants helps create a shaded, cool environment for the crabs. In addition, artificial shelters made from bricks or tiles can be placed in the pond to offer safe resting spots. However, these plants should not cover more than one-third of the pond surface to allow for proper sunlight penetration and oxygen circulation. It's also important to regularly remove any dead or decaying vegetation to prevent water pollution and the growth of harmful bacteria.
Second, maintaining clean water and adequate nutrition is crucial. The water quality in the crab pond should be monitored regularly, and leftover food and debris should be removed promptly. The water depth should be kept above 1 meter to provide enough space for the crabs to move and grow. Water changes should be done frequently, ideally in the evening, and each time at least one-third of the original water should be retained as bottom water to maintain beneficial microorganisms. During high temperatures, the frequency of water changes should be increased—typically every 3 to 5 days. The water source must be clean and free from pollutants.
To support crab development, the water should contain appropriate levels of inorganic salts, especially calcium, which is vital for shell formation. After each water change, small amounts of lime or other mineral supplements can be added to the pond. This is especially important during molting periods when crabs require more calcium. For example, applying about 5–10 kg of quicklime per 667 square meters after water exchange can help improve water quality and promote healthy growth.
Third, feeding practices should be carefully managed. Crabs should be fed a diet rich in plant-based foods to reduce reliance on animal feed. Foods like wheat, pumpkin, and soybean cakes are favored by crabs and should be prepared into pellets and placed on feeding platforms for easy observation and minimal water disturbance. The amount of food should be adjusted based on daily water temperature and the crabs’ previous day’s feeding behavior. Typically, feeding should be around 10% of the total crab weight, with a slight surplus left for two hours after feeding. Feeding times should be consistent, ideally between 4 and 5 pm, to align with the crabs’ natural nocturnal activity patterns.
Finally, preventing escape and disease control are critical during the hot season. Daily inspections of the pond should be conducted to monitor crab behavior, check the integrity of escape prevention structures, and look for signs of disease or predators. If any damage is found, the facilities should be repaired immediately. Predators such as frogs and water rats should be removed to protect the crabs. Disease prevention is also essential; using disinfectants like bleaching powder can help control potential infections. Any sick or dead crabs should be investigated promptly to identify the cause and take necessary actions to prevent further losses.
By following these steps, you can create a healthier and more productive environment for river crabs during the summer months.
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