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Second, strengthen the management during the seedling release.
Do not ignore the clearing of the pond. The crabs that have just entered the pool are very weak, and if the clearing of the pond is not complete, it will seriously affect the survival rate of the crab seedlings. Clear pond work is usually carried out 10 to 15 days prior to the release of crab seedlings. Lime or other drugs are used to remove the predators. One week after the clear pond can enter the water, when entering the water must be strictly filtered with 40 to 60 mesh sieve cloth, prohibited from entering the pool of enemy pests.
When laying seedlings, pay attention: 1 temperature difference between water temperature is less than 3 °C, it is best not a temperature difference, put the seedlings must be measured before the water temperature to be aware of. 2Before restocking, we must wait until the toxicity of the drug is completely disappeared. The method is: You can use a glass to take a glass of water and look at the light. If there are many zooplankton, it means that the efficacy can be released. 3 Before the crabs enter the pool, it is best to pour some water on the crab seedlings box. Because of the long-distance transport of crab seedlings, the cavity loses most of its water. If it is suddenly put into the pool, it will cause death due to water absorption. Therefore, some water should be poured first, and the crab cavity should be filled with water and then put into the pool. in.
Third, consciously control the growth of crabs.
How to control the crab growth to about 160 or less per kilogram?
First of all, increase the stocking density from the previous 250 grams of crabs to 500 grams (about 80,000). The crabs cultivated in this way increased from the original 80/kg to 160/kg, and the density increased, the growth slowed, and the size became smaller. After the emergence of seedlings, we must also look at the survival of crab seedlings. Generally, after the crabs become small crabs, the number of birds per acre should reach 30,000, and this kind of density can hope to cultivate a better crab.
Second, control the bait. Basic bait to develop better ponds, generally do not feed in another two months or so bait, individual ponds lack of natural food, you can add some food, but a small amount. In this way, the crab specifications of the first two months are controlled at about 2 grams. Two months later, feed some shredded bait such as mixed fish and feed it once a day. The amount is 5% to 20% of the body weight of the crab, depending on the growth, and artificially control its growth from the bait. In addition, it is necessary to strengthen daily management so as to inspect the ponds on a daily basis, observe the activities of the river crabs regularly, and periodically throw lime in the pool to improve water quality, measure body weight and body length every month or ten days, grasp the growth of river crabs, and make records. Easy to manage and summarize experience.
Three Technical Links in Pond Culture of Crab
First, create a pond condition suitable for cultivation of crabs. The water source in the pond should be sufficient, the water quality should be fresh and pollution-free, and irrigation and drainage should be convenient. The soil is preferably clay. The area of ​​the pond should not be too small, and the water should not be controlled too small. It is better not to be less than 3 mu. In the pool, there should be a beach for crabs to feed and occupy one third of the pond area. A certain number of aquatic plants should also be transplanted in the pond to provide a quiet environment for the river crabs to hide from the enemy and the oyster shells. It can also be used as a supplementary feed for river crabs, and at the same time improve the water quality and prevent the pool water from becoming fat. The silt in the bottom of the pool should not be too much, the oxygen consumption in the sludge is too large, and the water quality is liable to be deteriorated. Generally, the thickness of the sludge is required to be 15 cm. The anti-escape facilities should be built on the bank and cannot be built on the slope of the bank, and the height is 50 The centimeter is appropriate, and the inward slant angle is 15 degrees. Generally, it can be formed by double plastic.