Culture techniques of river crab in spring

At present, the water temperature is gradually rising, and doing a good job in the production of river crabs in spring is the first step to win the high yield of river crabs all the year round.

Clear pond disinfection

After a year of breeding in the pond, the bottom of the pond accumulates a certain amount of silt, which will become the best place for the reproduction of various bacteria and parasites, so before the crab species are released, the pond is thoroughly cleaned and disinfected during the idle pond in winter and spring. The specific measures are: thoroughly drain the pool water, let the sediment be fully frozen, and accept sunlight exposure, in order to achieve the purpose of killing pathogens. In addition, the quicklime (60~75kg/ mu) was sprinkled evenly throughout the pool while it was hot, and the mud and lime slurry at the bottom of the pool were fully stirred with a long-handle rake the next day to thoroughly kill the pathogen. At the same time, heighten and strengthen the dike ridge to prevent the flood pool from escaping during the summer flood season.

Timely stocking

The release of crab seeds should be completed by the end of March. Choose the authentic Yangtze River juvenile crabs with strong physique, no disease, no injury and complete appendages. The size of the crab is about 200 / kg, and about 800 crabs per mu.

Control water level

In order to promote early feeding and early growth of river crabs, the pond water should be reduced to about 30 centimeters in sunny weather. Under the sunlight, the water temperature rises rapidly to facilitate the feeding and growth of river crabs. In case of continuous overcast and rainy weather, the depth of the pond water should be increased appropriately to prevent the water temperature in the pool from changing too much.

Timely bait

In the middle and late March, the water temperature in some areas can reach more than 10 ℃, and the river crab begins to feed, and its food intake increases gradually with the increase of water temperature, so the principle of feeding should be grasped. In spring, concentrate is the main feed, supplemented by 15-20% roughage. Note: all moldy feed must not be fed.

Timely release of snails and transplanting aquatic plants

It is necessary to put snails into the pond before Ching Ming Festival, because the snails propagate before and after the Qingming Festival, which can provide high-quality and palatable animal bait for the crab species in the pond, with an amount of 500 snails per mu. Some aquatic plants should be transplanted or planted in March, and the area of aquatic plants should cover 20% of the pond area. Verticillium verticillata is the best, followed by Ellosia and Sophora flavescens.

Remove the moss in time

The water temperature is low and the water quality is thin in spring, which is suitable for the growth of moss. Once the moss propagates in large quantities, it will be disadvantageous to the growth of river crab. The following methods can be taken to clear:

1. When a small amount of moss appears, the method of manually removing or raising the water level and fertilizing the pond water can be taken to prevent the moss from reproducing.

2. When a large number of them appear, moss net and other drugs can be used to kill them, but the shelling peak of river crabs should be avoided.

Do a good job of disease prevention and control

Diseases should be prevented from April. At this time, rotten limbs, carapace ulcers, ciliates and other diseases are most likely to occur. The following measures can be taken to prevent the occurrence of these diseases.

1. Sprinkle disinfectant on the whole pool every 15 days or so to prevent the growth of a large number of germs. Drugs are: bromochlorohydantoin, dibromohydantoin and so on.

2. Use insecticides once a month. Drugs are: crab an, Xian Chong Ke, Xian Chong Jing and so on.

Use a course of internal medicine to mix and feed around March and April, and it is best to use it every half month in May. Specific drugs are: enteritis killing, norfloxacin and so on.