A reader from Guanzhen Town, Yuxian County, called in and mentioned that he had stocked 20 kilograms of crabs at a rate of 200 per kilogram in 10 acres of crab ponds. He asked whether it would be possible to introduce some crayfish into the same pond and, if so, how many crayfish should be stocked per acre.
According to Chen Huangen, head of the promotion department at the Jiangsu Provincial Aquatic Technology Extension Station, crayfish and crabs compete for oxygen, aquatic plants, and both have a tendency to attack each other. Traditional practices often avoid keeping crayfish in crab ponds due to the risk of predation and aggression. However, based on practical experience, it is possible to raise crayfish alongside crabs, provided certain precautions are taken.
First, maintaining a good plant cover is essential. Since both crabs and crayfish feed on aquatic plants, it's important to ensure that more than 50% of the pond area is covered with vegetation. This helps reduce competition between the two species. It's best to introduce crayfish after the plants have matured.
Second, proper feeding is crucial. Ensuring enough food for both crabs and crayfish can prevent them from attacking each other. Accurate monitoring of their numbers in the pond is necessary. When feeding, it's recommended to provide sufficient fresh snails—more than 250 kg per mu (approximately 0.067 hectares), ideally between 250–500 kg. The feeding strategy should follow the "two fine and one thick" principle. If large amounts of feed are used, water quality must be carefully managed to avoid deterioration, which could lead to the death of both crabs and crayfish.
Third, during the early stages of crayfish cultivation, it’s important to fertilize the water and apply appropriate base fertilizer to cultivate small zooplankton, which serves as natural food for the crayfish.
Typically, a stocking density of 2,000–3,000 crayfish per acre is considered safe. Overstocking can lead to breeding failure. Throughout the growing period, using traps or cages to catch and remove larger crayfish helps maintain lower densities, ensuring better growth conditions for the crabs.
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