In order to improve the survival rate of young crabs and increase economic benefits, crabs should be raised first. At present, in order to make the big-eyed larvae reach the commercial crab, most of them adopt temporary rearing technology in plastic greenhouse. Choose one with good water quality and sufficient water resources; Note: The pond with convenient drainage, no water leakage, no water seepage and little silt should not be too large, the water depth should not exceed 1.2m, the east-west direction of the pond is good, and the sunshine is sufficient. Please refer to the construction method of agricultural vegetable greenhouse for the construction of greenhouse.
15- 20 days before the crab seedlings are released, 75 kilograms of quicklime should be sprinkled on each mu for disinfection. After the medicinal properties disappear, it is necessary to feed water with an 80-mesh sieve to cultivate basic bait, transplant aquatic plants (which must be strictly disinfected), and set up necessary escape prevention facilities. Crab seedlings can be shallower when they enter the pool. Conducive to improving the water temperature and the growth of algae and aquatic plants in the water. Feed bait 2-3 times a day, such as soybean milk, fish, shrimp paste, etc. , and feed in the surrounding shallow waters, and feed at 4% of the body weight, and always pay attention to the weather, water quality sanctions, individual growth, and the number of organisms competing for food. With the growth of young crabs, we should also add some plant bait, such as duckweed and other high-quality aquatic plants. In daily management, we should pay attention to water quality regulation, grasp that water quality should be fat and cool, change water frequently, and change water less, so as not to cause drastic changes in water temperature and water level. After about 2 months of cultivation, crabs can be detained.
(2) Adult crab culture
Adult crabs like the clear and transparent water environment, rich in aquatic plants and rich in bait, which is most suitable for the growth of river crabs. At present, it is mostly cultivated in ponds, lakes, rivers and rice fields. Now give priority to with the pond for a brief introduction:
1, pond conditions
Clay, sandy soil or sub-sandy soil with sufficient water, convenient water intake and drainage, good water pollution and good ventilation are beneficial to the growth and reproduction of aquatic plants, benthic insects, snails and water worms. The old pond should be thoroughly dredged, the silt should not exceed 20cm, and the pond area should not be too small. The water depth of the pond is kept at about 0.6- 1.5m all the year round, and varies from place to place, with the shallowest point 10cm. Several mounds slightly above the water surface can be built in the pond, that is, crab island, where aquatic plants can be transplanted. The pond should not be too steep, and the slope ratio is generally below 1: 1.5, otherwise the river crabs will grow easily. You can also build artificial caves.
2. Transplant aquatic plants
The natural yield of Eriocheir sinensis mainly depends on the number of aquatic plants and benthic organisms (bait organisms) in the waters. In the process of aquaculture, it is an indispensable technical measure to plant aquatic plants well. Planting aquatic plants can not only feed crabs and supplement vitamins for ten days, but also support fighting and concealment, which is a powerful measure to improve the survival rate of river crabs in various periods. In addition, it can absorb harmful ammonia nitrogen, carbon dioxide and organic matter in the pool, release oxygen and stabilize water quality. The masses often say that "the size of crabs depends on aquatic plants." Therefore, river crabs cultured in ponds should make great efforts to plant aquatic plants. Our aquatic plants mainly include duckweed, red duckweed, water hyacinth, water hyacinth, black algae, Ceratophyllum, Sophora alopecuroides, water peanuts and so on. Attention should be paid to disinfection and prevention when transplanting.
3. Escape prevention facilities
Escape prevention facilities mostly use plastic film, but also useful cement board, depending on their own situation.
4, pond cleaning and disinfection
Generally, the pond is disinfected with quicklime half a month before the seedlings are released, and the dosage is 75 kg per mu. On the one hand, it can kill pests, on the other hand, it can improve the bottom of the pond, increase the content of calcium ions in the water and promote the molting growth of Eriocheir sinensis. Fertilize in time after receiving water to cultivate algae and basic bait, and the transparency is generally maintained at 40-50 cm. If tadpoles or frog eggs are found, they should be taken out in time to avoid competing for food and hurting young crabs.
5, put the seedlings
Crab seedlings produced in the Yangtze River system are the best seed selection, requiring neat specifications, complete steps, strong physique, active crawling and no injuries.
Sowing and density, pay attention to temperature difference when sowing. Fish fry bought from other places can't be directly put into the pond. They should be soaked in water for 2-3 minutes, taken out and put into the pond 10 minute, and repeated for 2-3 times. Young crabs gradually absorb enough water, adapt to the water temperature, and then put them into the pond, which can improve the survival rate.
Density: At present, it is mostly polyculture, especially polyculture of fish, shrimp and crab, which will bring higher economic benefits. The density can be controlled within 1500 crabs/mu, and the specification is120-150 crabs/kg. If the conditions are poor or shrimp farming is the main thing, the amount of seedlings released can be reduced appropriately.
6. Daily management
(1) Feeding: The whole process of intensive culture in ponds mainly depends on artificial feeding, so the type and quality of feed have a great influence on the growth and development of river crabs. When feeding, we should adhere to the principle of reasonable collocation of fine, green and coarse, with animal concentrate accounting for 40%, aquatic plants accounting for 35% and other plant feed accounting for 25%. There are three main types of feed: ① ② animals: small miscellaneous fish in seawater and fresh water, corpses of various animals, snails, mussels, blood of livestock and poultry, fish meal, silkworm chrysalis and so on. ; (3) Botany: aquatic plants, duckweed, Alternanthera philoxeroides, black algae, etc. Commodity feed: sweet potato, hemp potato, grain, bran, feed bran, etc.
Like pond culture, the feeding method of river crabs is "four observations and four determinations", that is, watching seasons, weather, water quality and crab activities, timing, fixed point, qualitative and quantitative.
It depends on the season: young crabs should be fed some live animal feed in spring, and the amount of animal feed should be appropriately increased in the middle growth period of river crabs, especially in May-August. Plant feed is the main feed, and river crabs need a lot of nutrition to meet gonadal development in the later stage, so they should be fed more animal feed, so that the weight of river crabs will increase and the meat quality will be delicious. Feed distribution is generally 40% from March to June, 7-6540.
Look at the weather: feed more in sunny days, less in rainy days, stop feeding when it is sultry and windy before showers, and feed in foggy days.
Look at the water quality: the water quality is clear, it can be fed normally, and the water quality is strong. Reduce the feeding appropriately and change the water in time.
Look at the activities of crabs: