Fish fry pond is one of the key technical aspects of fry breeding and raising the survival rate. Because of their delicate body, fish fry require strict requirements on the weather, water temperature, water quality, cleanup of predators, and stocking operations. The fish farmers are slightly neglected, and fish fry are caused to various degrees of death, and the entire breeding process fails. To this end, the author summarized the technical points of the fish seedlings into ten aspects for reference.
First, check the clear pond effect. In the first 1-2 days before the fry, the empty ponds should be pulled several times with a dense mesh to check whether there are any predator creatures in the pond. If wild fish, frog eggs, cockroaches, aquatic insects, and other predators are found, clear the pond. At the same time, the net can also be used to fully dissolve the remaining clear pond drugs accumulated in the bottom of the pool to prevent damage to the fry.
Second, check the residual drug in the pond. If the toxicity of the drug has not completely disappeared, it may lead to poisoning and death of fish in the pond. The inspection method is: 1. Take half a barrel of bottom water, test the fish in the bottom water, or place the fish in a small cage in the pond and observe for 8-12 hours to determine if the fry can enter the pool. 2. The pH value of the pool water that can be measured by the quick lime pond is below 8.5, indicating that the toxicity has disappeared and fish fry can be released. 3. Observe the water in the pool. If there is a blister, it means that the toxicity has disappeared.
Third, check the pool of fat. Mainly based on the color, transparency and food abundance apology to judge. When the fry fishes are ponds, the pool water is grayish-white, yellow-green or light yellow, and the transparency is 30-35 cm. Each litre of water contains about 10,000 rotifers and the biomass is 20-30 mg/l. If the pool water is not fat enough, the fish will grow poorly due to lack of feed. So the compost should be composted or poured into the pool corner of Xiangyang to fertilize the water immediately. When it is found that the water quality is too fat, it should be diluted with water and then put the fish. For example, if the base fertilizer of the pond is too early and the peak of rotifers has passed, excessive zooplankton, such as blisters, will be generated in the pool water, which will inhibit the breeding of small zooplankton of the fry, and interfere with the activities and feeding of the fry. 3-O. 5ppm crystal trichlorfon Quanchiposa, kill 1-2 days after the fry, or more than 13 cm per acre stocking species of 300-400 tail fish to eat large zooplankton. At the same time, it can be judged whether or not the pond water is fat enough to be floated before the dawn, but the fish should be caught before the fry is released.
Fourth, timely pond. Fry hatching 4-5 days, visible two eye spots, a waist point, in normal swimming in the water, should be in time under the pond. When entering the pool too early, the fry is too tender and it is easy to sink into the sediment to cause death. If it is too late, it will affect the growth of the fry and the survival rate is low.
Fifth, stocking specifications should be consistent. The fry stocked in the same pond should be of the same variety and the same specifications, and should be enough to prevent the big fish from suppressing or eating small fishes and the appearance of irregularities.
Six, adjust the water temperature. When fish fry ponds, the temperature difference between the pool water and the fry container must not exceed 3°C. If the temperature difference is too large, it will be gradually adjusted, and the fish will adapt to the pond. For fish fry transported in plastic bags, the plastic bag should be opened first and slowly placed in a cage pre-placed in the fish pond until the water temperature in the pool is the same as that in the bag, so that the pool water is gradually mixed with the water in the bag. Minutes later, the fry and water are slowly poured into the cage, so as to adjust the temperature difference and the adaptability of the fry to the air pressure inside the bag, that is, “slow seedlings”. If the fry is directly poured into the pool from the bag, the mortality of the fry is very high.
Seven, after the fry are fed and then down the pond. The fry can be fed with egg yolks before the lower pond and one hen per 100,000 fry. The method is to fully cook the eggs or duck eggs, remove the egg yolk, use double gauze wrapped in the water, knead the egg yolk and splash it on the fry, and feed the yeast or rotifer. Insist on fry feeding satiety pond, its survival rate has increased significantly.
8. Choose the appropriate time, place and method of restocking. Fry stocking should try to choose sunny noon or afternoon, when the water temperature is high, dissolved oxygen is sufficient, is conducive to quickly return to normal activities after the fish pond. Avoid rain or windy weather or enter the pool at night. In the windy days, the seedlings should be placed on the top of the deep water to avoid the large number of deaths caused by the stormy fish fry blowing to the pool or pressing to the bottom of the pool. When raising the seedlings, slowly tilt the container of fish fry into the water and let the fry slowly swim out of the water or pull the seedling container back slowly. Do not pour the fry into the pool. In addition, do not leave the fish fry immediately after entering the pool, and wait until the fry spread into the pool and then leave. If the fish seedlings are found to be densely integrated, they should be splashed with water droplets to spread them into the pool.
Nine, the depth of the pool is appropriate. Requires the pool water to be 40-50 cm deep, so that the temperature of the sun can be easily increased, the light is sufficient, the water quality is easy to fertilize, and the food organisms reproduce quickly, which is conducive to the rapid growth of the fry.
Ten, stocking density appropriate. The fry were bred into Wuzi pools, and generally 200,000 to 250 thousand tails of carp fry or 1500-200,000 tails of grass carp, herring and carp seedlings were planted; if the fry were bred into summer sub-pools, 10 to 15 million of carp were released per acre. Tail, or grass carp, herring 80,000-100,000.

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