Cultivating fry requires higher technical requirements than breeding adult fish. This is because fish fry are small, have weak swimming power, have low feeding power, have poor resistance to external environmental conditions and invasion of predators, and are highly metabolically advanced. Therefore, it is necessary to develop the fish fry into fingerlings with a certain standard of physical fitness, and then adult fish culture. In the production of fry, the survival rate is often not high, and even the entire army has been destroyed. The underlying reason is that an important link in fry production fails to meet the conditions required for fry maintenance activities. Caused a large number of fish fry. Most fry cultivation methods in my area are to use fertilizer ponds and feed soybean milk. The combination of fertilizer and feeding is easier to master than single fertilization. Clear than the underwater pond large. It is a proven method. However, due to different levels of technology, the survival rate of fry cultivation is not very high. The production index for general fry cultivation is about 80% survival rate, 20 to 25 days of cultivation, specifications up to 3 cm. To achieve this goal, the following issues should be noted. one. To completely clear the pond, fertility and water quality fish ponds in addition to pond conditions require ample water injection, regular pool shape, less silt, flat bottom, the most important thing is to thoroughly clear the pond before sterilization and fertilization for food culture. Disinfection of clear ponds should use quicklime, which can not only kill wild fish, predators and pathogens, but also improve the quality of sediments and water quality. Fish ponds that stock fish fry can not have predator organisms. After the clear ponds, water must be used for the nets. Before the fishes are put in, nets must be used to keep the nets open. If you find fish that have not been killed in the clear pool, you should take timely measures. If the number is large, it should be from the new clear pond. To cultivate bait organisms to master scientific methods and time, fish ponds should be at the peak of rotifer breeding time. At this time, the rotifer biomass in the pond is large, and there are enough foods in the fish ponds to improve the survival of fry. Rate and growth rate. In some cases, due to delays in the stocking schedule, 003-0.05 ppm trichlorfon Quanchiposa can be used for sprinkling and appropriate fertilization to control the proliferation of Cladocera and extend the peak period of rotifers. The maximum number of rotifers that can be treated this way can only be extended by an additional 3 days. If the time of the fishery ponds is delayed repeatedly, they have to give up the pool. This should attract special attention. The eggs of the broiled squid can be put directly into the cultivating pool. The time should be set in the first four to five days after the formation of rotifer peaks. This allows the fish to obtain sufficient natural rotifers after hatching. Can greatly improve the survival rate of carp seedlings. two. Pay attention to the quality of the fry and the quality of the fry. The quality of the fry depends largely on the survival rate of the fry. The stocking of the fry should be well-timed. It is best when the fish is just eating. This means that the yolk sac has just disappeared and the body color has become black. tour. Too early or late affects the survival rate. In addition, the fry's constitution is also very important, healthy fry are generally the same size, fresh body, plump shape, swim lively. If the fish seedlings are muddy or sinking, sick fish are not easy to survive in the pond. Therefore, the quality of fry should be carefully observed when purchasing and selling fry, and the quality is not good. When fry stocking, pay attention to the difference between the water temperature in the nylon bag and the water temperature in the fish pond. Do not exceed 5°C. An excessive temperature difference is one of the reasons for the death of the fish under the pond. Note that the water temperature must be measured before stocking. three. It should be noted that stocking methods and stocking density fry stocking method should first open the nylon bag, roll up the bag, put it in the shallow side of the pool so that the water level in the bag and the water level outside the bag, with three sticks to support, so that the nylon bag Can stand water. Feed the yolk first. The method is to put a small amount of half-basin water in the washbasin, wrap the cooked egg yolk with a sieve of about 40 mesh, and rub it in the water in the wash basin to wash out the yolk. Rinse the egg yolk in the basin gently in a nylon bag and feed one yolk per 100,000. Fish can be released within half an hour after the fry is fed. Before the fish is released, check whether the fry is open for feeding. The inspection method is to use a white porcelain dish to take a little water in the nylon bag to observe whether the lower abdomen of the fish is yellow if most of the fry are found. The yellow spots on the abdomen indicate that the fry had begun feeding. The survival rate of these fry stockings is guaranteed. If the fish fry do not open their food, the natural heart is not the bottom, but it is not certain that the survival rate of the fry is not high, because if the fry are tender, they will leave the mouth for a period of time, and after the fish pond is put in, the natural drinks can also meet the fry's feeding. Needs, the survival rate will also be high. However, if the fry develops abnormally and cannot be opened, the survival rate will not be high. Feeding before stocking can make us aware. Another inspection method is to observe the density and activity of the fry every day in the pond for three to four days after stocking. The method is to observe carefully at the edge of the pool. Because the body color of the fry is similar to that of the water, it is generally possible to use a stick of grass to put it in the water and move slowly. Look at the fry in the upper layer of the stick. Each pool can observe several more points. Due to the different species of fry, the observations are also different. The white pheasant is generally found to be relatively good, and the yellow color of the calyx is not very good to observe. The puffer fish is often left undisturbed at the bottom of the pool. So observe carefully. After four or five days, the fry have grown up and the poolside is relatively rare. More than ten days later, fishes can be seen from time to time during feeding. The stocking density of fry is generally controlled at 12 to 150,000 per acre. It is not easy to put more. If the pond is relatively tight, it can put up to 300,000 tails. In the later period of high stocking densities, the floating head of the fry was severe, the fry growth was slow, and the postponement of the time of divergent ponds affected the rearing of fingerlings, and the risk was also high. four. We must strengthen management and pay attention to the cultivation of disease-resistant fry for only 20 days. It is not difficult to strengthen management. The usual day-to-day management is mainly feeding and patrolling ponds. For fry breeding and feeding, most of them use soy milk, and the average amount of feed is four or two (200g) soybeans per 10,000. Four times a day, 8 am and 11 am; 2 pm and 5 pm. The feeding method advocates “three sides and four full ponds†and “four sides and four full pondsâ€. Of course, the fry stocking should be started in Quanchipia in the beginning of the stocking season. The method of feeding after the start of transformation of fry nutrition should also be adapted to the fish’s diet. . There are two points to note when grinding milk: First, the time for soaking in soybeans should not be too long, and the time for dry beans to be saturated with water is the best soaking time. This is related to temperature, which takes about 6 to 7 hours at 25°C and 9 to 10 hours at 20°C. If the soaking time is too long, the soybeans will not only produce less pulp, but also the time for suspending the particles of the soy milk in water after the soaking is short, and the efficiency of the feed will decrease. The second is that the ground slurry can't be mixed with water. The water in the soybean milk will form a precipitate, directly affecting the effect of the feed. The total amount of water needed to grind milk is added evenly during the refining process. These two points should attract attention. After the fish fry under the pond, it is necessary to insist on the morning and afternoon afternoons to observe the change of color and the dynamics of fry. Remove weeds from the pool and remove frog eggs at any time. Please note: The frog eggs that have just been produced in the early morning float on the surface of the water. After the sunrise, the eggs sink into the water and are not easily detected. So in the morning, you should bring tools to remove the frog eggs in time. At the same time, we must also pay attention to the eradication of harmful insects (such as dragon larvae, nymphs, etc.) as well as harm to birds and water snakes. During fry breeding, water should be injected in stages. This is an effective measure to increase the growth rate and survival rate of fry. The method of water injection in stages is that when the fish is in the pond, the depth of the pond is 50 to 70 centimeters. Afterwards, the water is injected every 3 to 5 days and the water is injected 15 to 20 centimeters each time. During the cultivation period, water is added 3 to 4 times. When water is injected, it must be filtered with dense net in the water injection to prevent wild fish and other enemy organisms from entering the fish pond with water. At the same time, do not let water flow through the bottom of the pool and stir up the pool water. Staged running water is an effective method to prevent bubble disease. Bubbles occur from time to time in production. In severe cases, a large number of dead fish can be caused. Can not be taken lightly. Bubble disease generally occurs in fertilizer and water ponds, especially before and after noon on a windless sunny day. The intensity of sunlight irradiation is strong, the photosynthesis of phytoplankton is intense, and fish fry ingest micro bubbles in water. Make it buoyant, can not sink, float on the surface. Due to the small fry, standing by the pool is not easy to find. Therefore, we must adhere to the patrol pond at noon when there is no wind and hot weather. In order to find problems in a timely manner. In the hot noon, it is also possible to supplement water or add water by using a micro-flow method to prevent air bubbles. Found that bubble disease should be relieved by adding water immediately. There are also spilled salt water, with precipitation of organic matter, reduce the photosynthesis of phytoplankton, to control the development of the disease, but the effect is not obvious. The amount of visible disease use 5 to 10 kg per mu. If it is found late, it will cause different degrees of loss. So pay enough attention. Fives. Before going out of the pool to enhance the physical fry After more than 10 days of cultivation, grow to 2.5 to 3.0 cm can be out of the pond, in order to make the fish solid and sophisticated, can withstand the operation and bumps in the outlet and transport, reduce death, must be carried out Fish training. The method and requirement for fish training is to pick the net at around 10:00 a.m. on sunny days. The first net will pull the pool fish into the dense network, so that the fish will be tested in an intensive environment. Stop the fish for a while (about two or three minutes) and put the fish. Pull the second net every other day. Put the summer flowers into the cage after the net is lifted. Then remove the wild, count (or estimate) and put it back in the pool. If the pond or the transportation distance is closer to the third net summer flower, the pond can be discharged. If the transportation is far away, it is best to reload the fourth network. In addition, the number of times of exercise and the type of fish related to carp generally need three networks, white carp and carp need four networks. The network is usually pulled once every other day. It cannot be removed from the net. A pool can only be pulled once a day. More nets will damage fish mucus and cause serious death. Pulling nets, counting, loading, unloading, and releasing fish should be stable, accurate, and light, so as to minimize the chance of fish injuries. To improve the survival rate of transportation and stocking.
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