Crabs eat pests Rice provides an environment how to raise river crabs in rice fields

Raising River Crab in Paddy Field

1. Appropriate amount of fertilization: River crabs are not resistant to fertilizer and water, afraid of lack of oxygen, so crab rice fields should not be fertilized in large quantities. Fertilization principle: based on base fertilizer, supplemented by topdressing, generally topdressing rice once or twice during the whole breeding period. Manure 500kg, phosphate fertilizer 30kg, potassium fertilizer 10kg were applied to base fertilizer per mu, and urea was the main topdressing, 7-10kg per mu each time.

two。 Reasonable bait: to cultivate young crabs in rice fields, it is necessary to fertilize water before releasing seedlings. After the crab fry goes to the field, feed the soybean milk or egg yolk once or twice a day and sprinkle evenly. After 1 week, gradually change to paste bait, such as bean cake paste, vegetable cake paste, wheat bran paste, pumpkin paste, potato paste and paste made from some chopped animal offal, and feed enough aquatic plants. An appropriate amount of ecdysone was added to the diet during molting. In the fields where crabs are cultivated, before and after the Qingming Festival, according to the release of 500g crab species, put 50-110kg live snails to let them lay eggs and breed for river crabs, and appropriately assist in feeding some soaked or cooked wheat, corn and other plant bait. The period from July to October is the peak growth period of river crabs, and the feeding should be adequate, nutritious and fresh. Crab molting, it is necessary to add molting in the diet, or properly feed some high-calcium bait such as eggshell powder, bone powder, shrimp shell powder and so on. After October, the water temperature gradually drops, and the amount of feed can be reduced as much as possible. it is generally 5% of the weight of the crab, which is fed twice, accounting for 40% of the daily feed at about 8: 00 in the morning, and for the second time in the evening, accounting for 60% of the daily feed. Feeding should be timed, positioned, qualitatively and quantitatively.

3. To prevent pesticide poisoning: crab rice fields should be as few pesticides as possible, if drugs must be used, high-efficiency and low-toxic pesticides should be selected. When applying medicine, choose a sunny morning, first put dry field water, so that crabs, fish concentrated in the ditch, slip, and then spray, and try to spray on the stems and leaves of rice, reduce the amount of water and soil falling into the paddy field. Pay attention to observation after medication, find abnormal, immediately inject water, if there is no abnormality, then inject water in the evening of the same day.

4. Water quality regulation: the dissolved oxygen in the water of crab paddy field generally needs to be more than 5 mg/L, and the pH value should be 7.5-8.5. When transplanting seedlings, transplanting seedlings in shallow water, the water level is about 20 cm, and then the water level is gradually raised to 60 cm with the increase of water temperature and seedling growth. The water should be changed every 7-15 days after May. In the high temperature season, the water is changed every 2-3 days, and each time the water in the field is changed. When changing water, pay attention to the water temperature meter should not exceed 3 ℃ before and after changing water, and avoid changing water during the period of latent rest and best feeding of river crabs.

5. Disinfection and disease prevention: before stocking, river crabs were bathed with 0.2 mg/L malachite green solution. During the culture period, 1525 kg of quicklime was sprinkled and ditched every 7-10 days per mu, and oxytetracycline was mixed regularly in the bait.