What kind of water quality can be used to put fry into the pond?

Fish fry entering the pond is one of the key technical links to improve the survival rate of adult fish in the process of fish fry cultivation. Due to the delicate body of fry, there are strict requirements on weather, water temperature, water quality, enemy damage and operation when stocking. A slight negligence of breeders may lead to the death of fry in different degrees or the failure of the whole breeding process. In this paper, the technical points of pond fry are summarized into ten aspects for reference.

First, check the effect of pond cleaning. Before the fry go into the pond 1 ~ 2 days, pull the pond several times with a dense mesh net, mainly to check whether there are harmful organisms in the pond. If harmful organisms such as wild fish, frog eggs, tadpoles and aquatic insects are found, the pond should be cleaned again, and at the same time, the net can fully dissolve the remaining pool-cleaning drugs accumulated at the bottom of the pond to prevent fry from being harmed.

Second, check the residual drugs in the pond. If the toxicity of the drug has not completely disappeared, it may lead to the death of fish fry in Xiatang. The inspection method is: take half a bucket of bottom water, put the fry in the bottom water for inspection, or put the fry in a small cage in the pond for observation for 8 hours to 12 hours to determine whether the fry can enter the pond; The pH value of pond water can be determined by cleaning the pond with quicklime. If the pH value is lower than 8.5, the toxicity has disappeared and the fry can be released. Observe the water in the pool. If Daphnia exists, the toxicity has disappeared.

Third, check the fatness of the pool water. It is mainly judged by water color, transparency and the number of prey organisms. When the fry go into the pond, the pond water is grayish white, yellow-green or yellowish, and the transparency is 30 cm ~ 35 cm. Every liter of water contains about 65438 rotifers +00000, and the biomass is 20 mg ~ 30 mg per liter. If the water in the pond is not fertile enough, the fry will not grow well because of lack of bait. Composting or spraying decomposed manure slurry in the sunny corner of the pond should be done immediately to improve the water quality. When the water quality is found to be too fat, it should be diluted with appropriate amount of water before releasing the fish. If the base fertilizer is applied in the pond too early, the rotifer peak period has passed, and excessive macrozooplankton, such as Daphnia, will be produced in the pond water, which will inhibit the reproduction of small zooplankton and palatable fry and interfere with the activities and feeding of fry. Spraying 0.3 ~ 0.5 ppm crystal trichlorfon in the whole pond can kill it, and 1 day ~ 2 days, or more than 0/3 cm per mu/kloc-0, can release the seedlings of bighead carp. At the same time, the water fertility of the pond can be judged according to the weight of the fish head floating before dawn, but all the fish heads should be fished out before the fry are released.

Fourth, go to the pond in time. After 4 ~ 5 days of hatching, two eye points and one waist point can be seen. When they can swim horizontally in the water, they should calculate the time when they enter the pond in time. If you enter the pond too early, the fry are too tender and easy to sink into the sediment, which will cause death. If it is too late, the fry growth will be affected and the survival rate will be low.

Five, stocking specifications should be consistent. The fry stocked in the same pond should be stocked with the same variety and specifications at one time, so as to avoid the phenomenon of big fish suppression, eat small fish and inconsistent specifications.

Sixth, adjust the water temperature. When the fry enter the pond, the temperature difference between the pond water and the fry container should not exceed 3℃. If the temperature difference is too large, it should be adjusted gradually first, and the fry should be adapted before entering the pool. If the fry are transported with oxygen in plastic bags, the plastic bags should be opened first, and then slowly put into cages in fish ponds. When the water temperature in the pond is the same as that in the bag, the water in the pond and the water in the bag should be gradually mixed. After 20 minutes, the fry should be slowly poured into the cage with water to adjust the temperature difference and the adaptation of the fry to the air pressure in the bag. If the fry are directly poured into the pond from the bag, the fry mortality rate is often extremely high.

Seven, the fry are full before going to the pond. Egg yolk can be fed once before the fry enter the pond, and one egg yolk can be fed for every 654.38+ 10,000 fry. The method is to cook the egg or duck egg, take out the yolk, wrap it in water with double gauze, knead it into yolk water and pour it on the fry, or feed it to yeast or rotifer. Persist in eating in the pond, and the survival rate of fry can be significantly improved.

Eight, choose the appropriate stocking time, place and method. Fish fry should be stocked at noon or afternoon on sunny days as far as possible. At this time, the water temperature is high and the dissolved oxygen is sufficient, which is conducive to the rapid recovery of normal activities after the fry go into the pool. Avoid rainy and windy weather or entering the pool at night. On windy days, fry should be released in the upwind of deep water to avoid being blown to the edge of the pool or pressed to the bottom of the pool by wind and waves in the downwind, causing a large number of deaths. When throwing fry, the fry container should be tilted slowly in the water, close to the water surface to let the fry swim out slowly or pull out the fry container slowly, and the fry should not be suddenly poured into the pool. In addition, don't leave immediately after the fry enter the pool, wait until the fry disperse and swim into the pool before leaving. If you find that the fry are densely clustered, spray them gently with water droplets to disperse them and swim into the pool.

Nine, the depth of the pool water is appropriate. The depth of the pool water is required to be 40 cm ~ 50 cm, so that the water temperature is easy to rise after sun exposure, the light is sufficient, the water quality is easy to fertilize, and the bait organisms reproduce quickly, which is beneficial to the rapid growth of fry.