Through years of production practice, the authors now summarize the breeding techniques for high winter survival rates of pond fingerlings as follows:

First, the main reasons for the high winter mortality of fingerlings

1. Poor conditions in the pond. A small number of farmers mistakenly believe that winter cold fish do not eat less, as long as there is water in the pond to put the fish into it. So do not choose the size of the pond, do not talk about shallow depth of water, regardless of water quality fat, choose the pond as a species of winter pond.

2, fish quality is not good. Not only the individuals are small, but they are also physically weak, and some of them are also seriously injured. These fish species have less nutrients stored in the body and have poor resistance to disease, frost resistance and low oxygen tolerance, and have a high winter mortality rate.

3, the water is severely deficient in oxygen. There are several reasons for the lack of oxygen in wintering ponds: First, the ponds are too small, the water level is too low, the water quality is too bad, and the stocking density of the fish species is too high; Second, the body of water is too thin, and there are too few phytoplankton, affecting the ponds. The amount of oxygen production; Third, fertilization, feeding too much, so that water eutrophication, organic oxygen consumption too much.

4, the invasion of pests and diseases. Disqualification of fingerlings and incomplete pond clearing caused serious damage to the pests and increased the mortality of fingerlings.

5, ignore the winter management. A few species of fish breeders often set aside the fish species and never asked about post-release management. Snow covered the ice and it was not clear. After the water surface was frozen, it did not break the ice. The poor water quality never adjusted, let alone feeding fertilizer, disease prevention, and so on.

Second, the key measures for surviving high survival rate of winter fish

1. Pond conditions. Should have sufficient water, convenient water injection and drainage, no pollution source, an area of ​​2 to 3 acres, 2.5 meters above the pool pond height, pond embankment solid, no leakage, good fertilizer retention, silt thick bottom 10 to 20 cm, pool No weeds, rectangular ponds north to south. The water depth is required to stay above 2 meters and maintain a stable water level. In the cold season, the water level should be increased to increase the water volume. In particularly cold areas, it is best to build an overwintering pool in areas with hot spring water and hot water in the factory. Maintaining a relatively stable water temperature is an effective measure to reduce the overwintering mortality of fish species.

2, water quality requirements. In front of the fishery ponds, limed ponds should be used to disinfect the plants, and 80 to 120 kilograms of lime should be used per acre. After dissolution, the whole pond will be splashed with sprinkling. This will kill low-level wild fish that can kill ferocious fish and consume oxygen and fertilizer. The pH of the stable water is between 6.8 and 7.8. According to the pond's water quality, the base fertilizer and topdressing agent are also applied. When basal fertilizer is applied, 80 to 200 kg of human fecal urine is generally applied per acre of water. When top dressing, appropriate amount of urea or carbon ammonia or other available fertilizer is used to fertilize the water. A certain amount of plankton. When the pond water quality is too fat, it should be injected with new water to eliminate some of the old water and ensure that the pond's water quality is fresh, tender, live and cool. The inlet should be filtered with a dense mesh to prevent wild fish from mixing. The food organisms in the winter fertilizers not only can be used to supplement the metabolic consumption of fish, but also contribute to the abundant dissolved oxygen in the pool water due to the photosynthesis of the phytoplankton and create favorable environmental conditions for the wintering of the fish species.

3, water level control. The water level of wintering ponds for fish species should generally be maintained at more than 2 meters. Because the water level is relatively deep, the temperature difference produced when the water temperature changes is also small, and it is safer for the species to get through the winter. If the water level of the pond is too shallow, it is easy to make the water body freeze, relatively reducing the space of the water body and causing fish species to lack oxygen and frostbite.

4, scaffolding wind. In order to avoid the invasion of wind and snow, a certain number of windshields can be constructed according to the size of the pond surface. The wind shelter is made of straw or reed rods, and it is fixed at any position on the pond with bamboo poles or stakes. Its height should be 10-15 cm above the surface of the water. A certain amount of pigs and cow dung should be piled under the shed. The heat energy produced by the rot during the rot fermentation will facilitate the wintering of the species and also provide the fish species with bait.

5, timely and pond. November is a suitable period for fish species and ponds, because when the water temperature drops below 10°C, the fish species basically stop feeding. At this time, it is best to choose sunny and windless weather and pool. The pool is too early, the water temperature is higher, and the fish species are more active. In the process of operation, fish breeds are easily injured and the bacteria are infected. It is easy to cause oxygen deficiency in the pond. If the pool is too late, the operation is inconvenient, and it is easy to make Fish body frostbite. When the fish species is pooled with ponds, the fish should be soaked with 3% to 5% salt water for 5 to 10 minutes.

6, preferred fish species. In combination with ponds, select high-quality, robust, and larger fish species as overwintering species. High-quality, robust large-species fingerlings are resistant to cold and hypoxia and have a low winter mortality rate. When a fish species with a body length of about 10 cm is wintered, the mortality rate can be reduced to less than 5%. To obtain high-quality large-scale fish species, in addition to summer and autumn cultivation of enhanced fish species, especially in the autumn, high-quality feed should be fed during the early winter and feed management of pond species should be strengthened. In addition to feeding fresh grass fodder, herbivorous fish should also be fed a certain amount of high-protein feeds, including grain sprouts, malt, and nutrients. The filter-feeding fish should be used to fertilize the quality of water, so that the pond water is rich in food organisms to meet the needs of the fish feed, lay the foundation for safe wintering of fish species.

7, reasonable density. In the case of fish and ponds, density must be controlled. Such as stocking too thin, affecting the utilization of ponds, resulting in the waste of water, and overstocking easily lead to water body hypoxia flood ponds, affecting the growth of fish species. The stocking density must be adapted to local conditions. Generally, about 10 centimeters of fish are distributed per acre of water, and 10 to 20 centimeters of fish do not exceed 10 thousand. The time for the fish species to enter the overwintering pool should not be too late. Normally, it starts to be better when the water temperature drops to about 10°C, and generally cannot be lower than 6°C.

8, adjust the water quality. Adjust the water quality of the pond so that there is sufficient dissolved oxygen in the water to increase the size of the fish and the fullness of the fish. Production practices have proved that, under the same water conditions, the greater the specifications, the higher the survival rate; and when the fish species specifications are the same, the survival rate of the fish species with high fertility is higher.

9, strict disinfection. Disinfection of fingerlings in fish ponds can be carried out according to normal practice, but they must not go through the court, otherwise the consequences are very serious. In the course of the translocation of fingerlings and ponds, it is unavoidable that some individuals will be injured on the surface, and it is easy to infect hydromycosis at this time. Therefore, the disinfection of fish should be mainly based on the prevention and control of aquatic molds.

10, feeding fertilizer. After disinfecting fish ponds, they should adhere to proper fertilization and feeding in winter.

(1) Fertilizer application. For overwintering ponds that have not been replenished for a long time, fertilizers must be topped up soon after the ice seals. The methods are: a fish pond with a depth of 2 meters, 5 to 6 kg of urea (or ammonium nitrate), and 3 to 4 kg of superphosphate. Mix in a plastic woven bag with a gauze bag or a number of small holes and hang it under the ice to let it slowly release fat. Fertilizer can increase the oxygen source of the water body, but it can not be too fat, and it is usually better to maintain the water body's transparency at 25-30 cm.

(2) feeding of cake fat. It is better to feed cakes with powdered pancakes, but it is also possible to feed compound feeds. In the water temperature above 5 °C, 3 to 5 days feeding once, feeding the amount of 0.5% to 1.0% of the fish body weight is appropriate. If continuous sunny weather can increase the amount of feeding.

(3) Feeding manure. During the winter, the selected weather is sunny and good quality manure (human excrement or livestock excrement) is given in the afternoon from 1:00 to 3:00. This will not only promote longevity but also increase the survival rate of overwintering by 5% to 10%. If a certain amount of livestock manure is piled up in a pond, allowing it to ferment and heat, it can be used as fertilizer and water, and it can also increase the effect of water temperature, and it can also increase the survival rate of fish species in winter more than 5%.

11, strengthen management.

(1) Inject fresh water timely. During the winter, keep the pond water level between 2 and 2.5 meters. If the conditions are met, it is better to keep the micro-flowing water in the overwintering pond. This will not only maintain good water quality in the pond, but also reduce or control the thickness of the frozen layer and effectively increase the amount of dissolved oxygen in the water under the ice.

(2) Ice breaking and snow aeration. In the severe winter season, due to the relatively high stocking densities of the pond species, ice formation caused a tight seal to the pond, which could easily lead to serious anoxia and suffocation of fish species. Therefore, it is necessary to stick to the patrol pond every day. When the ice sheet is severely sealed, it is necessary to break the ice in time or to increase the oxygen in the pond, remove the snow and debris on the ice surface, and maintain the transparency of the ice layer so as not to affect the phytoplankton. The oxygenation effect of photosynthesis ensures that there is sufficient dissolved oxygen in the water. The southern region should pay attention to water quality regulation to ensure that the dissolved oxygen in water is more than 3 mg/l, the pH is between 6.8 and 8.0, and other toxic and harmful substances do not exceed the standard; the surface of the pool in the north generally freezes, and it is necessary to fight ice eyes frequently to facilitate profit. Gas exchange, snow removal after snow, increased transparency for phytoplankton oxygen production, if necessary, can be applied chemical oxygenation agent.

(3) Prevent and treat fish diseases. In the winter season, fish species are susceptible to hydromycosis, so care must be taken in the operation of ponds and ponds to avoid injury to fish. Saprophytic can be controlled by 0.1ppm potassium permanganate solution Quanchiposa, once every other day, two consecutive times. When sick fish or dead fish are found, they should be removed in time for destruction or deep burial to prevent the spread of germs.

(4) Management after the spring. When the water temperature rises to 10 to 15°C, normal feeding and fertilization can be performed. Began to feed in order to concentrate to the main material, a small number of multiple, the day after eating, as soon as possible after the winter to restore the constitution of fish, and enhance resistance to disease.

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