Prevention technology of crab molting

There are three reasons for not molting: first, the crab body is injured or sick, and can not molt smoothly; second, lack of nutrition, lack of essential elements such as calcium and iron for a long time, resulting in poor growth of carapace and difficulty in molting; third, lack of suitable molting environment, such as hypoxia, poor water quality and lack of shallow water (molting zone) and quiet and hidden places. River crab infected with disease often die of molting failure, so in all stages of river crab breeding should pay attention to disease prevention and treatment.

In order to feed scientifically and replenish nutrition, feeding in river crab culture is the key.

In the process of culture, it is basically divided into three stages, namely, the early, middle and later stages. The former and later stages are mainly fine bait, and the middle stage is the combination of coarse and fine bait. In terms of feeding quantity, the proportion in the early stage is large, the proportion in the middle stage is the second, and the proportion in the later stage is small (according to the ratio of body weight). If the quality of the bait is not good, lack of certain nutrients after long-term feeding, the river crab will get sick. Lack of vitamin C can lead to black Gill disease and blackbody disease; lack of calcium can lead to soft shell disease; and if the bait is not fed enough, it will kill each other. Therefore, whether the variety, quality and quantity of feed are scientific or not will directly affect the growth and molting of river crabs.

At present, it is not ideal for many professional farmers to simply feed with wheat bran and cakes. When molting, a large number of baits containing calcium, iron and phosphorus should be supplemented, and at the same time, a certain amount of essential amino acids should be added to the diet. At ordinary times, quicklime should be sprinkled regularly to the pond to increase the concentration of calcium ions in the water and play the role of disinfection at the same time. During the molting period, the river crab should strengthen its nutrition so that it can eat well, not a good meal, a bad meal, a full meal and a hungry meal. Bait is generally carried out at 5: 6 p.m.

In order to create a suitable molting environment and keep the water level relatively stable, there should be both shallow and deep water areas.

Floating plants and submerged plants are cultivated in shallow waters or shoals in ponds to facilitate the concealment and protection of river crabs from external interference. The suitable cultivation area is 1gram, 5cm, 1ax and 3 on the water surface. When there is not enough bait at ordinary times, aquatic plants can also be used as auxiliary bait. in addition, aquatic plants can also improve water quality and ecological environment.

Pay attention to adjust the water temperature, the pond culture crab water is usually relatively small, so the pond water temperature difference is large, especially in the high temperature season, it is necessary to do a good job of cooling to keep the water temperature at 19: 28 ℃.

Strengthen pond patrol and record

Patrol the pond three times a day, one in the morning, one in the middle and one in the evening, and often pay attention to the eating situation of river crabs, check the activities of molting crabs, and clean up the molted crabs and dead crabs in time. The water temperature and air temperature are measured once every morning and afternoon, and the average water temperature and air temperature of each month should also be mastered. The body weight and breastplate width of river crab after molting were measured, and the records of breeding river crab were made.