Crab culture technology in box

The demand of crab in life is still very big, many people like to eat crab in life, the nutritional value of crab is very high, it is rich in protein content, so many people like to eat crab, but crab is cool, so the editor reminds everyone that although crab is delicious, it should not be gluttonous.

Pond conditions and facilities for raising crabs

According to the living habits of river crabs, crab ponds need to meet the following conditions:

① area is moderate, generally 3500 square meters ~ 6670 square meters.

The ② pond is rectangular and east-west, with a slope ratio of 1 to 2.5 meters and a depth of 1 to 1.5 meters. It has strong water retention and no leakage.

③ soil is clay loam, the bottom silt should not be too thick, so as not to prevent the river crab from living in caves.

④ environment is quiet, the slightest disturbance will affect the feeding and molting of river crabs.

⑤ excavates a circular crab gathering ditch with a width of 4 m ~ 6 m and a depth of 0.6 m ~ 1 m along the slope foot of 2 m ~ 3 m around the crab pond. The edge and middle of the slope is a large platform, or a crab trench is dug in the middle of the crab pond, and the two sides of the trench are large platforms.

Aquatic plants such as water peanut and water hyacinth are planted in the ⑥ crab pond, accounting for 1 / 5 of the crab pond, and bitter grass and verticillium verticillata are planted at the bottom of the pond to simulate the natural ecological environment.

The anti-escape facilities of the crab pond are mostly fenced by polyethylene net, with 3 × 3 polyethylene mesh sheet (whichever is the crab cannot escape) on the ridge of the pool, the net height is 1 meter, it is buried in the soil 0.2 meters, the unearthed part is 0.5 meters, and another 0.3 meters is used as a cover net, which is tilted 45 degrees with the wall net, and then the plastic film with a width of 0.3 meters is tied to the cover net.

Selection and release of crab species

Crab species should choose high-quality Yangtze River crab species with fast growth, strong physique, complete limbs, complete carapace, active crawling, neat specifications, no injury and no disease. The release time is from December to March of the following year, and the specification is 80 ~ 120 pieces per kilogram, 15kg ~ 20kg and 1200 ~ 1600 pieces per 667m2. From 15 to 20 days before stocking, 60kg ~ 80kg quicklime was sprinkled in the whole pond after melting and disinfection was carried out in the whole pond. After the toxicity disappeared, 800kg ~ 1000 kg of fermented livestock and poultry manure was applied every 667m2, and new water was injected to improve the water quality. Soak the crab seeds in 0.0002 ‰ malachite green or 3%-4% salt water for 3 to 5 minutes. If you buy crab seed from other places, you should soak the crab seed in fresh water for 1 minute, take it out and place it for 5 minutes, and then soak it for 1 minute. Repeat this for two or three times, so that the crab species slowly absorb water, rinse off the foam, and then sterilize and breed.

Stocking should choose sunny and warm weather, put the crab species evenly on the edge of the pond around the crab pond, let it slowly climb into the water, do not directly pour into the pool in piles. When stocking, the operation should be light, so that the crab species are evenly distributed in the pond, so as to improve the survival rate of stocking. At the same time, crab ponds cannot mix ferocious fish with bottom devouring fish such as common carp and crucian carp, because the growth of river crabs is mainly accomplished by molting, and freshly molted crabs are like a piece of tender meat and are vulnerable to swallowing fish. Therefore, there can only be an appropriate amount of mixed culture of upper filter-feeding fish (such as silver carp, bighead carp, etc.) in the crab pond.

Feed for river crabs

River crab is an omnivorous aquatic animal, the feed must be fresh, usually fed once a day before and after evening. Feed is put in the shallow water on the edge of the pool, and multiple tables are set up. Feed should be started when the water temperature is above 10 ℃. The proportion of daily feeding to the body weight of river crabs is: March to April 1%, May to July 5% to 8%, August to October more than 10%. Feeding should be timed, positioned, qualitatively and quantitatively. Generally, animal feed (wet weight) 3 kg ~ 4 kg and commercial feed 2 kg ~ 3 kg are needed for every 1 kg of commercial crabs. In addition, the proportion of feed distribution for the whole year is 40% for animal feed, 25% for bran and cake, and 35% for green feed.

Daily management and disease prevention

1. Patrol the pond every morning and evening, observe the feeding and growth of river crabs, check whether there are holes in the pond ridge or block, whether the escape prevention facilities and the net cover of the inlet and outlet are damaged, so as to prevent the invasion of escaped crabs and enemy attacks.

2. Water quality management river crabs have higher requirements for water quality, such as dissolved oxygen more than 4 mg per liter, pH 6.8-8.7, and transparency about 40 cm. In order to increase the water temperature and promote growth in spring, the water level can be controlled at 0.6 m ~ 0.8 m, and the water temperature rises in summer and autumn, and the depth of the pool is controlled at 1 m ~ 1.5 m. At the same time, the water is changed frequently, the water is changed every 7 days in spring and every 2 to 3 days in summer and autumn. The amount of water changed is 1 / 3 of the pool water, and the temperature difference of the water is controlled within 3 ℃ by irrigation while draining. If it is found that most river crabs come ashore, spit out foam, and breathe oxygen in the air, especially during the day, a large number of river crabs climb out of the water without going into the water, or as soon as they get into the water, they come ashore again, indicating that the water quality is deteriorated or seriously lack of oxygen. Chen water should be replaced quickly at this time. In addition, the whole pond should be sprinkled with raw calcareous water regularly to improve water quality, increase calcium, promote the growth of river crabs and molt smoothly. In general, quicklime is used at a depth of 1 meter per 667 square meters, 15 kg ~ 20 kg each time, once a month in spring and once a month in summer and autumn.

3. Disease prevention and control in high temperature season, it is easy to cause all kinds of diseases of river crabs. Prevention is more important than treatment, supplemented by drug prevention. It can be alternately sprinkled with 0.001 ‰ terramycin powder, 0.0005 ‰ ~ 0.001 ‰ furazolidone, 0.0005 ‰ crab Anling and other drugs. Often feed bait, 0.1 ~ 0.2 grams of oxytetracycline or erythromycin mixed bait per kilogram of crab. Proper amount of shell meal, bone meal, fish meal, egg shell powder and molting element were added to the feed to increase the elements such as calcium and iron in the feed to facilitate the molting of river crabs. Parasites can be sprinkled with 0.005 ‰ ~ 0.01 ‰ formalin or other appropriate insecticides in the whole pool, and bacterial venereal diseases can be disinfected and sterilized in the water body for two or three times, and the effect will be better if the whole pool is sprinkled with bait.

When it comes to crabs, the first thing that comes to mind is the crabs in Yangcheng Lake, because the crabs in Yangcheng Lake are mainly famous for their roe, so it is necessary to raise crabs with more roe, which is related to the area of the water where they are farmed. Therefore, it is very important to build a good crab pond.