Nowadays, fish production in aquaculture has developed a lot, but the overwintering technology for cultivating fish species and fish species has not yet been recognized and mastered by aquaculture. In fact, it is not difficult to do a good job of wintering the fish species. According to the actual situation and according to their needs, taking effective measures can improve the survival rate of the species.
(a) Appropriate food and beverage insurance. Generally warm water fish, when the water temperature drops to about 10 °C, although its appetite has an impact, but its digestive function is not very weak, there is still a certain demand for fertilizer, feed. When the water temperature drops to 7°C, the eel and squid will also filter in small quantities. The grass-eating fish will also feed on the surface of the water (cabbage leaves and other green materials). When the water temperature drops to 4°C, the fish species will be dormant.
(b) The density should be moderate. As the water temperature decreases, the amount of fish activity decreases accordingly, and the oxygen consumption also decreases accordingly. Therefore, the density of overwintering fish species may be appropriately greater than the feeding period. However, the density cannot be increased blindly. At the same time, different species and specifications of fish species have different oxygen consumption, and it is necessary to leave room for stocking, generally when the oxygen content of the water is reduced to 3 mg/L, but the winter phytoplankton photosynthesis is released. The amount of oxygen is also low, preferably above 5 mg/l as a safety factor. The management should regularly measure dissolved oxygen in water. Whether the stocking density of overwintering species is better depends on the size and species of the species, the condition of the pond, and the geographical location. If the water source conditions are good and there are less mud in the pond, put it in place. If the water depth is less than 1.5 meters and the fish species size is 13-20 centimeters, the ponds with difficult water intake should be reduced by about 20%.
(c) Maintain a certain temperature. Although fish are hypothermic animals, when the water temperature drops to 1-0°C, generally warm-water fish enter a state of paralysis. Fish will also die if the water temperature is below 0.5°C. Therefore, the water temperature in overwintering fish ponds should be kept below 4°C. Due to climate change in nature, some areas are cold and there are prolonged frosts. In the meantime, we can adopt the following methods to increase the water temperature: (1) Add new water to raise the water temperature; (2) Spread straw on the water; (3) During the winter A wind barrier is set up on the north side of the pond; (4) pigs and cow dung are applied near the pond. These insulation measures should be done before the onset of the cold.
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