During the wintering season, especially in some small fish ponds, the general mortality rate is as high as 10% to 20%. The causes of death and remedial measures are as follows. First, the cause of death 1. Small fish species and poor health. During the wintering period, most fish do not generally feed, have less activity, and have slow metabolism. It mainly sustains the accumulation of fat, protein and other nutrients in fish. In particular, fish species with too small specifications have poor health and cause death due to diseases such as infection with water mold during the process of pulling nets and pooling. 2. The wintering water is severely deficient in oxygen. Causes of hypoxia are: (1) The pool is lean and the number of phytoplankton is low. (2) Due to the accumulation of fertilization, feeding, and fish metabolites in the water body, organic matter increases and the oxygen consumption is too large. (3) Too much oxygen is caused by excessive density of wild fish or stocked fish species. (4) The influx of living or factory sewage into the water body causes a large amount of oxygen consumption and causes insufficient dissolved oxygen. (5) Poor soil water retention performance, a large drop in water level, shallow water causes hypoxia, and fish activity space is reduced. 3. The fish was injured. When pulling nets and ponds, due to poor operation, the fish may be injured or the scales may be wiped off; the invasion of the bacteria is also easy to die. 4. Poor management. Failure to check the amount of dissolved oxygen in the water body, fish movements and changes in the water body, or the failure to take any remedial measures in time has led to the death of fingerlings. Overwintering ponds, shallow water levels, excessive ice thickness, and ice and snow cover can also cause oxygen deficiency in the pool water and cause the fish to suffocate and die. 5. Poor watering or oxygenation. For a long time, blindly circulating flushing or oxygenation caused the pond water temperature to drop rapidly and the fish was frozen and frozen to death. Second, remedial measures 1. Fish selection for wintering ponds. (1) Choose a leeward sunny pond as a wintering pond. (2) The wintering pool is generally 3 to 5 mu, which is conducive to enhancing the thermal insulation performance of the pool. (3) The pond should have good water retention and fertilizer retention, and the bottom of the pond should preferably be loam or clay soil. The pond that is seriously leaking cannot be used as a wintering pond. When using a natural pit as a wintering pond, the bottom of the pond should be flat. The less the water grass and silt, the better. The silt should not exceed 30 cm in thickness. (4) A certain water temperature should be guaranteed. The depth of water should be 2 to 4 meters. The best source of supplemental water is the river water, reservoir water, and spring water. (5) If the dissolved oxygen level is too low, the process should be increased. Industrial wastewater or a large amount of domestic sewage inflow should not be used as a wintering pond. (6) For tropical warm water species, plastic greenhouses must be constructed on the pool to keep warm. 2. Cultivate large-size fish species. Large-sized fish species are robust, plump, cold-tolerant and hypoxic, and have low mortality. 3. Fish pond disinfection. Before entering the overwintering pool, the fish species shall be sterilized with quicklime clear ponds, and the fish shall be put into the pond after the drug effect is passed. When entering the pond, the fish body shall be soaked with 5% salt solution for 5 minutes. Careful attention should be paid during the pooling process to avoid bruising, scraping or stepping on fish. 4. Timely and appropriate stocking of fingerlings. The stocking time should not be too early or too late. Generally, stocking at a water temperature of about 10°C is better, but not less than 8°C. The stocking specifications require large-sized fish species with robust physique, and the general species is more than 10 cm. This will not only increase the ability of fish species to escape the enemy, but also greatly increase the survival rate of overwintering. The stocking density must be adjusted according to local conditions. 5. Strengthen wintering management. Regularly check the water quality, water color and species activity. In sunny weather, it can be combined with the needs of fish species and fed properly. Regularly fill water in ponds with seepage, and take timely measures if problems are found. Kn95 disposable face mask, kn95 , disposable face mask, face mask , mask , breathing vavle Kn95 disposable face mask, kn95, disposable face mask, face mask, mask, breathing vavle Dongguan Marvec Electronic Technology Co.,Ltd , http://www.marvec-cn.com