The annual cultivation process of crabs can be divided into three stages: the early stage, the middle stage and the later stage. Scientific management should be conducted at different stages to effectively prevent and reduce the occurrence of crab diseases.
The early stage of crab breeding is from the seedlings to the early June in the coming of high temperature. At this stage, the water temperature is low, the water quality is good, the feeding is less, the crabs eat less, and the disease is relatively less. During this period, we must scientifically choose good-quality non-injurious seedlings. The newly-opened pond should be well-prepared for removing alkali and transplanting plants. When it is about to enter the high-temperature period, the crab pool should fill the water level in time. If the river water quality is not good, add water immediately after the use of external drugs to regulate water quality; if the pond water quality is not good, we must first discharge two-thirds of the old pool water, use 1 to 2 times of external use of drugs to improve the water quality, and then introduce Good water quality river water. Medicinal water quality control agents, speed Kang B type and fiber insects will be grams.
The middle period of crab breeding is from early June to mid-August. The temperature is high and it is the high incidence of various diseases of crabs. Use internal medicine and topical medicine once every 10 days to 15 days, and do not wait until the disease occurs. The topical drugs are mainly used to improve the substrate and water environment, and can use Baiao long-acting fungus, Qingkang B type, fipronil, chlorine dioxide, bromochlorohydantoin, etc.; internal medicine is used to enhance the crab constitution. Immunity can be improved by using Bioo Crab Additive, Shake-reducing King, Glycoprotein, Calyx and other drugs. For large lakes bred on the purse seine, precautions should be taken during flood seasons. Old meshes should be used as “bridgesâ€. One end should lead to the bottom of the pool, the other should float near the water surface, and the middle section should be inclined at about 45 degrees. Artificial bait is fed on the middle section of the net to guide the river crab into the upper water body. Slow-release long-acting fungus tablets are hung at the bottom of the pool to keep the bottom of the pool in a good environment. With a high-pressure water gun, the upper water or drug water is injected into the lower layer of the water body, so that the temperature difference between the upper and lower layers of water is reduced, so that the crab quickly adapts to the new environment.
The later period of crab cultivation is from the middle of August to the harvest period, which is the accumulation of nutrients and maturity of river crabs. Most of the mature crabs crawled ashore at night and rested in the water during the day. If there is little or no investment during the day, it is necessary to invest more at night, because mature crabs will only go ashore for crawling at night, and they will not eat enough bait during the day, which will result in insufficient nutrition for crabs. With a lot of physical exertion, crabs will gradually die. Found that mature crabs ashore, especially early crabs, to change to feed more during the day, less or no vote at night, combined with internal and external use of some drugs, seize the rejuvenation and fishing listed. Fully matured crabs, especially female crabs, at this time have reduced liver function, and the feeding of animal high-protein diets should not last more than 20 days. Otherwise, the crabs will die due to the inability of the liver to adapt to high-protein nutritional storage; On the one hand, mature male crabs forcibly mating with female crabs in fresh water can also cause death. When yellow crabs become blue crabs, fertilization should be carried out. The fertigation time should not exceed 20 days. After that, the food should be mainly sprouted wheat or hawthorn, pumpkin and other high sugar content varieties, and should not be fed high protein food.
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