Fry cultivation, also known as "hair pond." It refers to raising the fry for 20 days to 25 days and grows to about 3 centimeters, which is called "summer flower". The success or failure of fry cultivation directly affects the economic efficiency, but the fry generation rate of fry has been very unstable in production. After many years of practice and summary, the main reasons and solutions are summarized as follows:
First, the reasons affecting the rate of hair Tong
1. The number of fry and the survival rate of transportation are one of the reasons that affect the hair pond. Some nursery units are for profit, deliberately deducting the number of fry, and some are estimated that the number is insufficient, rarely reach 100%, and some are less than 70%, so this kind of originally inaccurate fry even if other measures are perfect, It is difficult to meet the number of ponds and affect the fat pond rate. In addition, due to the long-distance transport of fry, and not pay attention to changes in water and other measures on the way, resulting in lower pond after the fish fry pond rate decreased.
2. Fry quality problems. One is to buy inferior seedlings; the other is to take the outdated old seedlings. The rate of these two kinds of seedlings is very low.
3. The improper restocking method is the key to affecting the rate of issuing ponds. Most of the long-distance transportation of fish fry uses nylon bags to flush oxygen and transport of automobiles, and the water environment in nylon bags will change with the gradual extension of the time after sealing. The first is the temperature. The outside interference after sealing the container is very small, and the temperature in the bag is slightly higher than the temperature due to decomposition of fish metabolites and fish breathing. This situation generally does not cause death in transit, but after reaching the destination, the water environment in the local fish ponds is very different from the quality of the water used for the transportation of fry. Therefore, if it is improperly stocked, it is easy to make fish ponds because of the sudden changes in the water environment. The survival rate has dropped, and even a large number of deaths have occurred. It is difficult to find small individuals because of the small number of fry. When the stocking was not tested, the toxicity of the pool water did not disappear, which was also the reason for the low rate of hair ponds. In case of windy weather, the location of the stocking was improper. If the fish pond was stocked in the downwind position, the fry could easily be caught in the water on the banks of the embankment and the constitution was slightly poor. The fry is difficult to swim in the top of the water, and many fry deaths due to excessive waves.
4. When the fry were in the pond, the predator organism affected the rate of the pond. Rearing of the fry is often due to improper fertilization time before the large copepods large-scale breeding in advance, as well as dragon larvae and pine algae, etc., they can directly harm the fry or swallow fry; In addition, the frog can not only directly butcher the fry, but also Fish fry competition for food; the other is in production practice, we found that there are a few fish ponds due to clear pond measures are not in place, there are many moss when the fish pond, the fry once entered it is difficult to escape.
5. Insufficient natural palatability feed. Three days after fry hatching, endogenous nutrients basically disappeared and they began to feed artificially cultivated palatable natural foods -- rotifers. Therefore, when the fry hatchlings should have enough palatable natural foods, the fish fry would be Loss of weight and death in a short time.
Second, the solution
1. Choose an honest and trustworthy field home to buy seedlings, when buying seedlings, it is necessary to make multiple proofs to reduce the error value, ensure the number of seedlings taken, strengthen the management of on-the-way transportation, and find problems in a timely manner, such as long-distance transportation, when bags are bagged Infused 400,000 units of penicillin to inhibit the oxygen and metabolism of the fry in the bag to ensure the survival rate of transportation.
2. Select the fry after hatching for 4 days to 5 days, the fish ticket has strong swimming ability, and the fish are stocked with high-quality fish.
3. Check if the toxicity of the clear pond drug completely disappears before the fish pond is under the pond. Inspection methods: (1) Put dozens of tailed seedlings into cages in the pond for half a day to one day to observe whether the fry activities are normal; (2) To test the pH value of the pool water, and to reduce the pH value to below 9 with quick lime, indicating that the toxicity has been Disappeared; (3) There was no helium in the observation pool, and there was a disappearance of toxicity.
4. Before the fish ponds, use a dense mesh net to empty the pond 1 to 2 times to see if any miscellaneous fish, frog eggs, aquatic insects and other predators are mixed in. If wild fish or predator creatures are found, clear the pond, Found large fleas or scale insects, can be used 0.3ppm crystal trichlorfon Quanchiposa, and then Mushi 3.5 kg to 4.5 kg of urea fertilizer water, when the fish ponds, the fish penicillin with 100,000 units / 10,000 disinfection.
5. The temperature difference at the lower pond does not exceed 5°C. When stocking, put the bag in the pool for 10 minutes and wait for the temperature to be similar and then open. After opening, pour a small amount of water into the bag, and then grasp the bag and shake it a few times to mix the water with the water in the bag. After about 10 minutes Pour into the cage against the surface of the water, and feed a cooked egg yellow slurry for every 100,000 fry in front of the lower pond. When stocking, firstly, the fish should be swept out of the water at the tip of the pond, 1 meter away from the pool. Avoid plunge fish.
6. According to the principle of adapting the natural palatability of the bait in the pond to the growth of the fry in the growth and development of the fry, timely cultivating the water quality, ensure that the rotifer peak during the peak of the fry under the pond, fish rear pond feeding fertilizer, water quality regulation and other management measures To keep up with the fact that everyone in the production process pays more attention to management, it is not introduced here.
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