Nowadays, it is a golden time for fry reproduction, hatching, and fry cultivation. Seedling cultivation is a commonplace for fishermen. All fisheries have managed to improve the survival rate of fry cultivation in spring fry cultivation, but in recent years, fry cultivation has become a survival rate. It is generally low, usually only about 30%, which affects the aquaculture efficiency. The author believes that in order to improve the survival rate of fry, we should grasp the following ten points: First, the choice of fry pool The fry pool requires a solid embankment, no water leakage, adequate water, convenient drainage and drainage, and the pond should be leeward, rectangular, east-west direction . The fry pool should not be too large, the water body should not be too deep, too large and easy to form wind waves, fish fry collision with the pool wall, affect the survival rate; too deep, the water temperature is difficult to increase. The area is too small, the water temperature changes quickly, and the living conditions of the fry are difficult to control. Second, fry before stocking completely clear pond fry 10 days before stocking, pumping pool water, remove weeds, digging too much silt, with 1500 kg of chunks of lime per hectare after the whole pool spilled to kill bacteria, parasites And predator creatures. When entering the water, the inlet should be filtered with a double-layer dense net to prevent wild fish from entering the pool. After the fish pond is filled with water, it is necessary to regularly inspect the pond every morning to find the frog eggs and aquatic plants. Third, the scientific quality of fish fry fry, directly affect the survival rate of fry, identify the quality of fry methods are: 1. In the hatching tank, the water stirred into a swirl, fry can swim against the edge of the water is better seedling. 2. Take a small amount of fry into the dish, the fish are active and clean, the body is clean, the mouth is blown to the surface, and the fry can swim against the water. After the water is drained, the fry is left struggling vigorously at the bottom of the pan, and the head and tail are bent into loops as good seedlings. Fourth, the preparation before the pond 1. "Test water" after the pond. One day before stocking, take a few fish fry in the fish pond cage and observe for one day. If the fish activity is normal, you can put the seedlings. 2. Fertilizer pond. The criteria for fertilizer ponds is that zooplankton (rotifers) are at the peak of their breeding season. After ensuring that the fish are in the pool, there are natural foods with adequate palatability, which can improve the survival rate of fry cultivation. After 6 to 7 days of fertilization in general fish ponds, rotifer breeding reaches a peak period, so the fertilization time should be 7 days to 8 days before the fry. If the water temperature is low, it can be 2 days to 3 days in advance, applying 200 kg to 300 kg of organic fertilizer per acre. 3. Feed the pond. When the fry were in the pond, each 10,000 fry were fed with 2 to 3 egg yolks by placing the fry in a slightly larger plastic pot, diluting the egg yolk with water and filtering it through a 40-mesh polyethylene mesh cloth and evenly spraying it in the basin. Wait for 20 minutes before putting it in the pool. 4. Adjust the temperature of the pond. When the fish is transported to the pool mouth, note that the temperature of the oxygen bag and the fish pond can not be different by 3°C. If the temperature difference is too large, the oxygen bag should be placed on the surface of the fish pond. When the water temperature in the bag approaches the temperature of the fish pond, slowly put the fry into the pool. . In case of storms, the upper hand should be placed 2m to 4m offshore. Fifth, the stocking density should be reasonable Fry breeding generally only one species breeding pond, not polyculture, 80,000 to 100,000 fry rearing fish per acre. Density is too low to make full use of water bodies and bait. If the density is too high, the floating head of the fry can be easily caused during the cultivation process, or the growth of the fry can be inhibited due to insufficient feed. Sixth, cast enough food, timely fertilization of fish fry cultivation mainly to soy milk, supplemented by fertilization. Soybean milk spilled more than once, spilled evenly, and used it as a "three times two full ponds" (that is, three times a day, three times a day, including two full ponds, one spill around the fish pond). The ground is now splashing, can not be put on hold too long, every kilogram of soybeans per acre needs 3 kg to 4 kilograms, after 5 days, in addition to the pulp also need to increase the investment of bean dregs, bean cake paste and other fine material. Fertilization can increase water nutrient elements and promote the growth and reproduction of natural food organisms. When the water in the fish pond is light and the natural food is not enough, it is timely to top-dress. General fish fry 5 days into the pool, every 2 to 4 days topdressing 1 times, each time organic fertilizer applied per acre 80 kg to 100 kg, to ensure that the fish pond has a certain natural food organisms for fish feeding. 7. Rehabilitation of water quality In the early stage of watering into the pond, the water depth is controlled between 40 cm and 60 cm, which is conducive to raising the water temperature and growth of the food organisms. After 7 days, water injection is conducted every 2 days to 4 days, each time 10 cm to 15 cm. , To expand the growth space for fry, keep the water "fat, live, cool, tender". Water injection should pay attention to the flow of water into the pool straight, the water injection time can not be too long, so as not to prolong the flow of fish, consume physical strength, affecting growth or triggering the racehorse disease. Eight, regular patrol ponds Each morning and evening patrol ponds one by one, observe the water quality conditions to determine the number of feeding and fertilization, observation of fish activity and growth, found that the disease should be promptly treated and removed. Nine, do fish disease prevention and control work fry summer flower stage, the main fish diseases are horse disease, whitehead white mouth disease, white skin disease. During the cultivation period, lime water is splashed once every 5 days to 7 days. Each time, 15 kg of lime are used per acre to clarify the water quality and prevent fish diseases. When the racehorse disease is onset, it is possible to cut off the fry mad swimming route and stop the water injection, and increase the amount of feeding and fertilizer appropriately. When whitehead white beetle disease and white skin disease occur, 1 g/m3 of bleaching powder or 0.2 g/m3 of strong chlorine is sprayed in the whole pool per acre to disinfect the pool water for 2 days, and the pool is divided in time to reduce the density in the pool. Ten, timely fry fish by 20 days to 25 days of cultivation, grow to more than 3 cm, it is necessary to timely sub-pool, reduce the density of the pool to promote summer flower growth and improve summer flower out of the pool specifications. Before the summer flower goes out, it takes 2 days to 3 days to pull the net to exercise. Before pulling the net, it is necessary to stop for 1 day. The operation should be light and the speed should be slow.
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