CATDOLL : CATDOLL: What conditions are needed to raise crabs?

What conditions are needed to raise crabs?

The land does not occupy land, the water does not occupy water, "one land for two uses, one water for two breedings, one land for two harvests, and a three-dimensional ecological breeding model combining planting and breeding. The specific conditions are as follows:

1. Rice field selection and engineering construction: Crab farming rice fields should be located close to water sources, with good water quality and convenient water inlet and outlet.

2. Stocking of crab seedlings: In production, it is advisable to adopt the method of adding fertilizer and water to the pond.

(1) The crab seedlings must be at least four days old when the zoeae have transformed into megalopause (i.e. crab seedlings).

(2) The crab seedlings are desalinated for more than 24 hours at a salinity of 3‰ to 4‰.

3. When purchasing crab seedlings, the quality of the crab seedlings should be identified. The identification method is as follows:

(1) The individual sizes of megalopa larvae should be uniform.

(2) The crab seedlings are strong and active. For good quality crab seedlings, drain the water, grab a handful with your hands, gently squeeze them, and place them on a flat surface. The crab seedlings will quickly spread out.

(3) When crab seedlings reach the requirements of stage V, they can be put into the field for breeding. Before being put into the field, aquatic plants should be planted in the rice fields. The varieties of aquatic plants should be diversified, and as many types of aquatic plants as possible should be grown in the fields. The various aquatic plants should be sparsely, evenly, and mixed with each other in the shallow water beside the fields, ensuring that the coverage rate of aquatic plants in the crab ditch reaches about 30%.

How to raise crabs?

A. Greenhouse conditions The test greenhouse is a steel frame double-layer solar panel insulation greenhouse with an area of ​​1,200 square meters (20×60) and a water area of ​​1,000 square meters for seedling cultivation. It is equipped with aeration and oxygenation facilities and pipeline heating equipment. The greenhouse has a light transmittance of about 50%. Five 200-watt incandescent lamps are installed for nighttime lighting. In order to facilitate the uniform feeding of feed, three sidewalks are set up. B. Preparation before seedling release About 10 days before seedling release, 30 cm of water is released and strictly disinfected with 100ppm quicklime emulsion. After disinfection for 24 hours, the oxygenation facilities are started for oxygenation. Next, water plants are released. The water plants are mainly water peanuts. The water plants retrieved are soaked in high-concentration lime water or potassium permanganate solution for 24 hours, then rinsed with clean water and evenly released into the greenhouse. The area of ​​water plants released accounts for about 80% of the water area. Then gradually heat the water to 20-22℃. C. When releasing crab seedlings, the crab seedling transport box should be placed in the water first, soaked for about 30 seconds, then taken out of the water, left for about 5 minutes, and then placed in the water for 30 seconds. Repeat this 4 to 5 times before releasing the seedlings. Choose a place without aquatic plants, gently grab a handful of seedlings, and shake them slowly so that the crab seedlings can be evenly dispersed into the water. Although after 3 hours of transportation, there is almost no death of megalopa larvae. D. Daily feeding and management In the early stage of crab seedlings entering the pond, they are mainly fed with tofu, fish paste, chimney worms and other baits. Use a 40-mesh mesh to filter the tofu into tiny particles, and then add water to evenly sprinkle the whole pond. After washing the small fish, use a beater to make fish paste, add 1% salt and add water to evenly sprinkle the whole pond. The daily feeding rate is 100% to 150%, and feeding is 4 times a day, that is, before dawn, noon, dusk, and midnight, and the lights are turned on for 2 to 3 hours during midnight feeding. When the crab seedlings have basically grown to the stage II juvenile crabs, the main feed is bean cakes and fish paste, and tofu is occasionally fed 1-2 times. The bean cakes are still made into small particles after being cooked. At this time, the feeding rate is controlled at about 100%, and feeding is still done 4 times a day. During this period, water is gradually added to 0.5 meters. After reaching the V stage, the feeding rate is 60%-80%, and the bait is still mainly bean cakes and small fish. Feeding is done 3 times a day, and no feeding is done at midnight. During the entire seedling raising period, observe the activities and feeding conditions of the crab seedlings, estimate the number and weight of the crab seedlings in the pond, and determine the reasonable feeding amount. During the period when the crab seedlings are concentrated molting, the feeding amount can be appropriately reduced, and the lighting time can be increased at night. Daily management work mainly controls water quality and disinfects regularly. Every week, 5ppm lime emulsion is mixed with water and evenly sprinkled throughout the pond to add some calcium and maintain the pH value of 7.5-8.5; 50% stable chlorine dioxide 0.5ppm is used for disinfection every 10 days, and the water is changed once every 15 days, with a water change volume of about 30%, and some new water is added appropriately, and the water level is controlled at about 0.5 meters. When changing water, the inlet and outlet are covered with 80-mesh sieve silk to prevent the seedlings from being discharged or other harmful organisms from coming in. Pay attention to the temperature difference within 5℃, and it is best to keep the water temperature basically the same. Usually pay attention to the growth of aquatic plants in the pond and add some fresh aquatic plants in time. E. Cultivation results In short, the key technology for cultivating large-sized juvenile crabs in greenhouses is: selecting excellent seedlings, determining reasonable stocking density, and strengthening daily management.