First, water quality regulation 1, deepen the water level. When the hot season has come, the water should be added to the deepest part of the year. During the hot season, the maximum suitable water level can be maintained between 1.2m and 1.5m; when the temperature is particularly hot, the water level should be deepened, preferably around 2m. 2, frequently change the water. During high temperatures, the crab pool should be replaced with fresh water to ensure good water quality. The water source for replacement should be fresh, clean, and free of pollution. Do not replace the field water, industrial waste water, and domestic sewage that have been treated with pesticides into crab ponds. The time for changing the water can not be carried out when the noon is hot, generally changing the water when the early and late weather is cool. Normally the water can be changed every other day. When the water temperature exceeds 28°C, it is best to change the water once a day. The amount of water exchanged should not exceed 1/3 of the original pool water. 3, diligent fishing grass. Ponds raise crabs. Since there are few natural plants growing in the pond, you can go to the wild river ditch or waste water to collect fresh plants and put them into the pool. You can also plant plants by hand to let the crabs ingest food, inhabit, shade, and reduce summer heat. Water temperature. The sinking water, floating water, and high-water plants in the pool each account for a certain proportion, and the total grass surface coverage should be controlled at about 1/3, so as to leave more space for the crabs to move freely. The types of aquatic plants include Xiaoqingping, Hydrilla verticillata, and water peanuts. During the high temperature period, the aquatic weeds will rot for a long period of time, and we should adhere to the principle of less groundless fishing. It was found that the aquatic plants were not fresh, the grass blades were yellow, and the stalks were soft and should be removed to prevent their decay and damage the water quality. 4, regular improvement of water quality. Regular use of microbial agents, such as photosynthetic bacteria, EM bacteria, etc., applied once every 15-20 days, can effectively reduce the content of ammonia nitrogen, nitrite, methane, hydrogen sulfide, and promote the balance between the bacterial phase and the algae phase. Sprinkle quicklime regularly, and 15kg of quicklime can be used per acre pond every 15-20 days. After adding water, the whole pool will be spilled and it will be conducted every 20 days or so. It is also possible to regularly use bottom modifiers or water improvers to improve water quality and sediment quality. Second, reasonable feeding in the hot season, crabs in addition to the high water temperature at noon, hidden underwater and aquatic grasses, the morning and evening when the weather is cool, generally out of activity, foraging, and a larger food intake. At this time, sufficient food supply should be ensured to promote the growth of crabs. Feeding of bait should adhere to the reasonable mix of animal and vegetable feeds to ensure the overall demand of nutrition for crabs, and avoid bait-feeding with single species and nutrition. Can be fed melon slices, leaves, rice buds, aquatic plants, cooked corn, wheat and other plant-based feed, with the feeding of small trash fish, snail meat animal food, the best feeding of crab grain feed. No matter what kind of feed, it should adhere to the principle of freshness, deliciousness, and quantity. It is better to observe a slight surplus within 2 hours to 4 hours. The specific standard should be about 8% of the body weight of the crab. Ultimately, it should be adjusted flexibly according to weather, water quality, crab pond conditions, etc. Feeding time is good for morning and evening, and the feeding place can be in the water grass and the place where the water temperature is lower. Third, the disease to prevent the hot season, crab pond water temperature is high, the water is easy to deteriorate, crab disease resistance is weak, attention should be paid to the prevention of crab disease. Summer is the peak season of crab, mainly ciliate, black shank, trembling disease, edema disease. The main principle of prevention and control of crab disease is “to prevent the main and to prevent it from governing.†Disinfect the bacteria and parasites by regularly spraying bleaching powder, chlorine dioxide and other disinfecting drugs. Regularly sprinkling biological agents (such as photosynthetic bacteria and EM bacteria) to regulate water quality. Regularly add allicin, three yellow powder, vitamin C, and polysaccharides to the feed. Such drugs as baits for feeding, can effectively prevent the occurrence of crab disease. Found dead crabs should be immediately removed, and find out the reasons to take measures to prevent the spread of crab disease.
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