The key to prevent cold damage in fish ponds in winter

In cold and cold winter, fish ponds often freeze to death, starve or suffocate because the water surface is too thick. Doing a good job in the prevention of cold injury in winter and making fish safe through the winter can lay a good foundation for the strong growth of fish in winter, stocking next spring and early listing, and greatly improve the benefit of fish culture. Years of practice has proved that the main measures to prevent cold damage of fish are as follows:

1. Protect against cold damage in deep water. Choose a pond with a leeward direction and a water depth of more than 2 meters, which can make the fish survive the winter safely. At the same time, the overwintering pool water can not be in a static state for a long time, and part of the pool water is usually replaced every 20 to 30 days, and each time the total pool water is replaced by 1GB, 4pm, 1ax, 5pm, so as to prevent water pollution. If possible, we can also make use of natural environmental conditions such as hot spring water and underground deep well water to survive the winter.

two。 The hole in the wall is protected against cold damage. The cold damage can be prevented by setting up cold-proof and wind-proof walls and cold shelters. The specific method is to build a wind barrier of more than 2 meters high with straw or soil on the north side of the fish pond, and a dustpan on the east and west sides to reduce the attack of the north wind. Drainage ditches should be built around the pond to prevent stagnant water from flowing into the pond and reduce the temperature of the pool water. The wall of the north wind shield can be dug 40 cm away from the bottom of the pool. Two cold shelters with a depth of 2 meters and a diameter of 0.8 meters can be dug. The walls of the cave can be built with bricks or ceramic pipes, and fish can hide in the shelter when the cold wave strikes. Practice has proved that this method has the advantages of cold protection, low cost and obvious effect.

3. The greenhouse protects against cold damage. On the basis of setting up wind barrier and cold proof tunnel, the effect of building plastic film cold proof greenhouse is better. The method is to use bamboo or wood along the edge of the pond to build a "human"-shaped roof, the distance from the ground to the roof is about 2.5 meters, covered with two layers of plastic film, connected with the edge of the pool to form a sealing cover, the film can be sealed with soil around. The area of overwintering ponds is generally 40 square meters, the water depth is more than 2 meters, cement ponds and soil ponds are available, and the stocking density can be determined by water temperature, water quality and water quantity. Generally, 15 fish can be released per cubic meter of water, or 300 fish species below 10 centimeters. In ponds with better conditions, 30 fish can be released per cubic meter of water, and 400 fish species can be released. The running pond can refer to the high-density stocking capacity of running water culture, which can keep the dissolved oxygen in the pond water at 2 mg / L. At night or rainy days can be covered with thick grass curtains to maintain the temperature in the shed, sunny days should be opened grass curtains and other covers, the use of solar energy to increase temperature. When the water temperature is too high, it should be ventilated and filled with some new water.

4. Warm up and protect against cold damage. ① steam heating: set up a stove next to the overwintering pool and boil the water with an iron pot, so that the steam from the pot lid on the special bamboo tube enters the overwintering pool through the connected hose to increase the water temperature. ② infrared lamp heating: in the overwintering pool covered with plastic film greenhouse, a 250W infrared bulb is installed every 35 square meters of water, 30 cm from the water surface, and a piece of thick papery or other water-absorbing material is fixed about 60 cm above the bulb to prevent the water condensed from water vapor from falling on the bulb and causing the bulb to burst or misfire. Turn off the lights when the water temperature rises to 20 ℃. The infrared lamp has the advantages of large heat, rapid temperature increase, low power consumption, simple installation, sterilization and prevention of diseases such as water mildew in fish.

5. Add materials to prevent cold damage. The feeding of bait, especially the feeding of high protein concentrate, should not be ignored during the overwintering period. Feeding concentrate with high protein content can improve cold resistance and prevent the physical decline of overwintering fish. Attention should be paid to nutritional collocation, especially the balance of amino acids and the adequacy of vitamins and trace elements. In general, the protein content of feed for fish during overwintering should be about 25%, while that of tilapia can be lower at about 20%, but it should be high in energy, such as fine bran, wheat bran, bean cake, malt and so on. and often with some green duckweed, fresh vegetable leaves. The soft-shelled turtle can improve its resistance to adversity mainly through intensive cultivation. Soft-shelled turtle needs nutrition before and after overwintering. First of all, the supplement of energy and protein should be strengthened. The fat content can be increased to 3% to 5%, and as much as possible to feed some fresh feed, and targeted supplements of vitamins, calcium, phosphorus and so on. Lack of sunlight in winter is prone to lack of calcium, and more phosphorus is needed to increase yolk deposition. The soft-shelled turtle needs more B vitamins, vitamin A, vitamin D, vitamin E and choline during the overwintering period than during the normal feeding period, so these substances should be increased appropriately. All fish feeding concentrate should also achieve "three determinations", that is, quality, timing, and quantity.

6. Increase oxygen and prevent cold damage. If the river freezes too thick and the water under the ice is anoxic, the fish can be suffocated to death. At this time, it is necessary to immediately sweep the snow, break the ice, change water in time, start oxygen-increasing machinery, and regularly apply microbial preparations to improve water quality. In particular, silver carp and bighead carp in some "old water" ponds are also easy to suffer from diseases such as anchor head disease under the condition of hypoxia, so while increasing oxygen, insecticides should be applied in time to effectively control cold damage and diseases.