The latest scientific culture technology of river crab

With the rapid development of the domestic economy, the special aquaculture industry is gradually rising, and the national living standards and consumption standards are also gradually improving, so some seafood products are also slowly appearing on the dinner table, so breeding river crabs is of great economic value. Mastering the culture technology of river crab is very important for farmers to get rich, so let's follow the editor to learn it:

The latest scientific culture technology of river crab

Pond condition

The water source is adequate, the intake and drainage is convenient, and the water quality is good without pollution. Clay, sandy soil or sub-sandy soil is selected for good ventilation, which is conducive to the growth and reproduction of aquatic plants and benthic insects, mussels and water earthworms. The old pond should be thoroughly desilted, the silt should not exceed 500px, and the pond area should not be too small. Pond water depth varies, the shallowest 250px, the pond can build several mounds slightly higher than the surface of the water, that is, crab island, the island can be transplanted with aquatic plants, the pond is not too steep, slope ratio is generally more than 1RU 1.5, otherwise, the river crab is easy to dig holes, and is not conducive to climbing out of the water at night. Artificial caves can also be built.

Transplant aquatic plants

In the process of breeding, planting aquatic plants is an indispensable technical measure. In addition to supplying vitamins for crabs, growing aquatic plants can also reduce the role of fighting and concealment, which is an effective measure to improve the survival rate of river crabs in each period. in addition, it can absorb harmful ammonia nitrogen, carbon dioxide and organic matter in the pond and release oxygen and stabilize water quality. The main species of aquatic plants are duckweed, Manjianghong, water hyacinth, water floating lotus, verticillium verticillata, goldfish algae, bitter grass, water peanut and so on.

Clear pond disinfection

Generally use quicklime to clear the pond for disinfection in the first half of the month, with a dosage of 50 to 75 kilograms per mu. On the one hand, it can kill enemy organisms, on the other hand, it can improve the bottom of the pond, increase the content of calcium ions in water, and promote the molting growth of river crabs. Fertilize in time after receiving water, cultivate algae and basic bait, transparency is generally maintained at 40-1250px, if found tadpoles or frog eggs should be removed in time, so as not to compete for food and harm young crabs.

Seedling selection and purchase: crab seedlings produced in the Yangtze River system are the best, with neat specifications, complete steps, strong physique, active crawling, no injury and no disease. Seedling release and density: pay attention to the temperature difference when releasing seedlings. The seedlings purchased from other places can not be put directly into the pond. They should be soaked in water for 2-3 minutes, taken out and placed for 10 minutes, and repeated for 2-3 times. After the young crabs gradually absorb enough water and adapt to the water temperature, they can be put into the pond to improve the survival rate. The density can be controlled within 1500 crabs per mu. If the condition is poor or shrimp culture can appropriately reduce the amount of seedlings.

The living habits of River Crab

Cave dwelling

River crabs like to live in caves on muddy banks or shoals of rivers and lakes, or hide in gravel and water plants. River crabs take digging holes as their instinct, and it is also an adaptive way for river crabs to defend themselves from enemy attacks. River crabs generally choose to dig holes on steep banks with hard soil, with a slope of 0.2 or 0.3, rarely on gentle slopes below 1.5-2.5, let alone on flat ground. This provides a basis for the construction of our culture ponds.

Food habit

The eating habits of river crabs are very miscellaneous. Under natural conditions, they mainly eat water plants and humus, eat animal carcasses, and also like to eat snails, clams, worms, insects, and occasionally cannibalize each other when there is a lack of food for small fish and shrimps. They even swallow the eggs they hold, and sometimes they compete for food of the same kind because of a dead fish. in general, it is easy for river crabs to obtain plant food, which often constitutes the main component of crab stomach food. There is also some sediment in the crab's stomach, which is a sign that the crab feeds on benthos and humus.

River crabs usually hide in their holes during the day and go out to look for food at night. On land, river crabs do not eat much and often drag the food on the shore to the water or to the edge of the cave before feeding. In the annual period, except for the low temperature dormancy, the crabs do not feed temporarily, even if they migrate in winter. When the water quality is good, the water temperature is suitable, and the bait is abundant, the river crab has a large amount of food, and it can continuously prey on several snails in one day and night. the soft-shell crab that has just molted its skin, and the disabled individuals are often harmed, but the river crab has a strong ability to endure hunger. If you don't eat for 10 days or even half a month, the river crab won't starve to death. Under the condition of artificial culture, according to the needs of the growth and development of river crab, mastering the structure of "fine-coarse-fine" in feeding feed is beneficial to the growth of river crab.

Daily management of river crab

1. Feeding: the whole process of intensive culture in the pond mainly depends on artificial feeding, so the type, quality and quantity of feed have a great influence on the growth and development of river crab. The principle of reasonable matching of concentrate, green and coarse should be adhered to when feeding. Animal concentrate accounts for 40%, aquatic plants account for 35%, and other plant feeds account for 25%. There are three main types of feed: full-price special formula feed for river crabs. (2) animal nature: small mixed fish of sea and fresh water, carcasses of animals, snails, mussels, blood of livestock and poultry, fish meal, silkworm pupa, etc.; (3) plant: aquatic plants, duckweed, water peanuts, bitter grass, verticillium verticillata, commodity feed: potato, potato, cereal, wheat bran, bran, etc.

2. Water quality management: River crabs have higher requirements on water quality than fish, especially more sensitive to polluted water. The quality of pond water is good, which is conducive to the growth and development of river crabs and the meat is delicious. The PH value of crab pond water should be kept at 7-9, the optimum value is 7.5-8.5. the dissolved oxygen in pond water should be kept above 5mg/L and lower than 5mg/L, which will affect growth. Below 2mg/L, river crabs will die. Adjust the PH value of the pond water, the water quality of the newly excavated ponds is mostly acidic, and the water quality should be improved regularly with quicklime mortar, which can improve the utilization rate of feed for river crabs and is beneficial to the smooth molting of river crabs, usually once a month in spring. Every 15-20 days, 7-10 kg of quicklime is used for 1 meter per mu of water depth.

3. Escape prevention: special personnel are on duty to patrol the embankment, especially on rainy days and when changing.

4. Patrol the pond: observe the water color, pay attention to the activities of the crab, do not hurt the river crab, and keep the water environment stable. When the gonadal development is plump and the price is suitable, the water can be drained and picked up.

Disease prevention and control of cultured river crab

In recent years, with the continuous expansion of the scale of raising crabs, crab diseases are also spreading and upgrading. Crab diseases that have never existed before also occur in large numbers, mainly ciliosis of young crabs and trembling disease of adult crabs, which bring huge economic losses to the crab industry. Therefore, the prevention and treatment of crab disease should give priority to prevention, early detection, early treatment, no disease prevention, early treatment, and take different methods to prevent crab disease at different growth stages. Photosynthetic bacteria, EM bacteria and other microbial preparations were selected to regulate water quality. Prevention such as quicklime and dibromohydantoin are used regularly in high temperature season. In the period of high incidence of ciliates, chitin or ciliate was used once every 15 seconds and 20 days. In order to avoid drug resistance, drugs should be used alternately. Trembling disease is a kind of microorganism between bacteria and virus. Using enemy to kill the pool is an effective method to prevent and cure trembling disease.

In the breeding of river crabs, from the selection of breeding sites, full efforts should be made, otherwise in the later stage of cultivation, the growth of river crabs will not be good because of the lack of preliminary work, and it will not help to solve the problem at that time. Therefore, in the breeding of river crabs, we must not take it lightly.