Through years of production practice, the authors now summarize the breeding techniques for high winter survival rates of pond fingerlings as follows:
Pond conditions should have adequate water supply, easy injection and drainage, no pollution source, 2 acres to 3 acres in area, 2.5 meters above the pond level, pond embankment is solid, no leakage, good fertilizer retention, silt thick 10 cm ~20 cm, no weeds in the pool, rectangular ponds facing 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.
The quality of water is required to be sterilized with quick lime in the pond before the fish ponds, and 80 kg to 120 kg of lime per acre. After dissolution, the whole pond will be splashed, and low-level wild fish capable of killing ferocious fish and aerobic fertilizer will be killed. , And can stabilize the pH of the water in the 6.8 ~ 7.8. According to the pond's water quality, the base fertilizer should be applied to the base fertilizer and the topdressing fertilizer. When the base 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 readily available fertilizer is used to fertilize the water quality. Cultivate 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.
The water level of wintering ponds for the control of fingerlings 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 can easily cause the water body to form a frozen state, which leads to the lack of oxygen and frostbite in the species.
Shed shelter wind In order to avoid the invasion of wind and snow, according to the size of the surface of the pond to build a certain number of shelters. 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 cm to 15 cm above the surface of the water. A certain amount of pigs and cow dung should be piled under the shed. The heat generated by the rot during the rot fermentation will facilitate the wintering of the species and provide feed for the species.
Timely ponds in November each year 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 best. 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 minutes to 10 minutes.
It is preferable to combine fish and ponds, and select high-quality, robust and large-sized 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.
The reasonable density is to control the density when fish species and ponds are used. 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 should be adapted to local conditions. Generally, about 10 thousand cm of fish species should be placed on the water surface per acre, and the species of l0 cm to 20 cm should 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.
Adjust water quality Regulate the water quality of the pond so that there is sufficient dissolved oxygen in the water to increase the fish size and plumpness. 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.
Strict disinfection of fish ponds can be routinely disinfected fish species, but 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.
After fertilizing the fingerlings and disinfecting ponds, the appropriate fertilization should be applied in winter.
Strengthen management (1) Inject new water in a timely manner. During the winter, the pond water level should be kept between 2m and 2.5m. If the conditions are met, it is better to keep 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. (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. (4) Management after the spring. When the water temperature rises to 10°C to 15°C, normal feeding and fertilization can be performed.
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