The nesting of other fish species is currently based on the mode of raising large crabs (about 500 per acre). To fully utilize water bodies, 10 to 30 tails per acre can be used for each type of acre and carp. 5 to 7 kilograms of heterotrophic silver carp and 2 to 3 kilograms of green prawns. In addition, from May to the beginning of June, 15 to 30 intensively cultivated carp species can be placed at a depth of 5 to 7 cm per acre. This is because carps are the main food intake for low-level trash fish and shrimps. Sets of squid can control wild crabs and shrimps in the crab pool that compete with crabs, fight for oxygen and compete for space.
Pay attention to oyster shell management Before the first oyster shell of the crab, attention should be paid to shallow water breeding, light enhancement, water temperature increase, and early food, feeding small trash fish or high-quality pellet feeds to ensure that the crabs have smooth shells for the first time. Outside the crab pond spilled medicine, fertilization should avoid the relative concentration period of crab shell, while grasping the law of crab shell, forecasting the next peak of the shell. The crab pool disinfection should be performed after changing the water 1 week before the peak of the oyster shell, and add about 1% of locust and (feed grade) calcium dihydrogen phosphate and fructooligosaccharides, vitamin C, Sanhuangsan, etc. in the feed. . The amount of feeding should be reduced during the peak period of clams, and attention should be paid to keeping the environment relatively quiet.
Control crab pond moss suitable for early water, keep the crab pool has a certain degree of fatness, transparency is 30 to 40 cm water depth, weakening the light necessary for moss growth, change before and after the Ching Ming snail into a snail. In the early stages of moss germination, copper sulfate and moss can be used to control the drug, but it is important to pay attention to the effects of moss-killing drugs on the growth of aquatic plants and the timely addition of water the next day after treatment. For ponds with small areas, it is best to remove them manually during the moss growth period.
Maintaining moderate levels of aquatic plants not only provides natural feed for crabs, but also regulates water temperature, provides shelter, absorbs nitrogen, phosphorus, and heavy metals in water bodies, prevents eutrophication and controls water pollution. Crab ponds need to be diversified, with submerged plants (Elodea, Vallisneria, etc.) as the mainstay, floating plants (water peanuts, water spinach, green grass, etc.) as the supplement, and a small amount of emergent plants (Artemisia, reeds) Wait). The distribution of aquatic plants in the crab pool should be sparse and dense, and the water grass coverage should be maintained at 60% to 70% during the crab growth period.
The timely introduction of snails to artificially put snails on the ground not only provides a good source of natural animal protein for river crabs, but also purifies the bottom water bodies. The first time of snail feeding was earlier. Normally, 150-200 kilograms of live snails were released per acre before Chingming to facilitate early adaptability of snails to the pond environment and produce young snails for early feeding. In June and August, it will be supplemented by one investment and put in 150-250 kilograms per acre. The two launches will prevent the large amount of water from being thrown at one time, causing the early water quality to be lean and the large amount of moss will affect the growth of crabs.
Rational feeding of feed according to the nutritional needs of various stages of crabs with a reasonable mix, requiring before and after the fine, the middle of the green, meat and vegetarian ingredients, Qingjing combination. The ratio of animal and animal diets was 60:40 before mid-June, from late June to mid-August 45: 55 to late-mid-October to 65:35. When feeding compound feeds, enzyme preparations should be added to the feed to increase exogenous enzyme-assisted digestion. The corresponding increase in feeding points, the main feeding in the evening, so that the feed can be eaten by the crabs in a timely manner, the loss of small waste, pollution is relatively reduced, is conducive to water quality management and disease prevention.
Increase the amount of water in the crab pool to maintain a reasonable depth of water. Install micropipe aeration facilities at the bottom; conditionally add new water gradually during the early period; increase the amount of water intake and the number of water changes during the period of 6~9 months. At 4 o'clock in the morning and rainy morning, it forms micro-flow in the water for a certain period of time to keep the water fresh; during the rainy season or during the hot season, in addition to the normal influent water, the chemical oxygenation agent (granular oxygen , Detroit, etc., generally used in the evening).
Pay attention to the regulation of water quality Water transparency should be maintained at a depth of 30 to 40 cm before the end of May, and then be maintained at more than 50 cm. From July to August, change the water every 7 to 10 days, each time changing the depth of water by 30 centimeters; from September to October, change the water once a week, changing the water every time by 1/3. At the same time pay attention to adjust the pH of the water body.
The use of biological agents microbial agents including EM bacteria, photosynthetic bacteria, etc., July to September crab ponds to be Quanchiposa 4 times, should be used on the premise of open aerator at 10 o'clock on the sunny morning, when used or after use 1~2 Hours supplemented with particulate oxygen (granular oxygen, etc.). Microbiological preparations cannot be used together with disinfectants, antibiotics, etc.
Prevention and control of diseases May be sterilized with bromochlorolamine once a month from May to June, 0.3 grams per cubic meter of water body; from July to September, let crabs take internal EM microbiological preparations for 3 days at a time; 10 to 11 months before the release of crabs 20 to 25 days can be used to kill ciliate drugs. At the same time, we must prevent predators such as water snakes, frogs, cockroaches, mice, crawfish, jaundice, and birds from attacking.
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