The breeding of Xinjiang black plover has not yet reached its scale. The seedlings mainly come from the Mainland. In order to meet the needs of the seedlings of Xinjiang Ukrainian aquaculture, we conducted breeding trials of the early-stage propagation of black mullet fry in May and June 1999. The experiment was carried out in the cement pool of the plastic greenhouse of the XPCC Aquatic Technology Extension Station on the fishery of the Wujiaqu Mengjin Reservoir. 12 groups of bred broodstock were divided into 4 batches. The first shipments were made on April 30. 25,000 hatches were hatched. On June 10, 14,000 fish species of 6 to 8 centimeters in length were bred and the survival rate was 56%. This is the best batch. The worst was the third batch. On June 4th, the production was delayed. 40,000 fry-fish fry were hatched. On July 10, 0-50 cm of 6-8 cm long fish were reared and the survival rate was 12.5%. The average survival rate is 28.5%. The progress of this experiment is summarized as follows:
1 Broodstock breeding
1.1 Source of broodstock: Select the broodstock that has reached 1kg or more of mature individuals in the self-education pond in our station.
1.2 Broodstock rearing: The broodstock should be placed in a 15-m2 cement pond for intensive cultivation about 1 month before the urine production (ie, at the end of March). Disinfect with bleach before putting fish. Then add 1m deep water. 2 fishes per square meter of water (1 to 2 kg/tail). Before the broodstock enters the pool, the fish is soaked with 4% salt solution for about 10 minutes. Let the fish adapt to the environment of the small water body first. On the third day, fresh fish fillets were fed, and the fish were sized to eat. In the afternoon, 1 in the afternoon. Pool water temperature is controlled between 20 and 25°C, and increased to 26 to 28°C one week before delivery. Change the water every 2 to 3 days, and remove the sediment that has settled at the bottom of the tank. The source of water is deep well water that has been preheated by aeration. The water hyacinth, which covers 1/4 of the water area, is shaded in the pond.
2 artificial labor
2.1 broodstock selection: female broodstock to choose to expand the abdomen, gently press the abdomen by hand feels soft and elastic, anal micro-projection and red. Male and female brooders chose slightly larger abdomen, slightly red anus, and obvious dark red stripes on both sides of the body. The male and female fish are easily distinguished at the time of labor. Individual males are generally larger than females. Females and males are paired by 1:1. However, when pairing between male and female fish, do not disparate too much to facilitate spawning and fertilization.
2.2 Types of oxytocin and unit dose: The oxytocin-releasing hormone analogues (LRH-A2), high-efficiency oxytocin mixture (RES) and domodione (DOM) are three kinds of oxytocic agents. Its matching form and unit dose are (1) LRH-A2.2ug+RES.5mg/kg fish; (2) LRH-A2.2ug+DOM.2mg/kg fish. For the pectoral fin base abdominal injection. The male dose is halved. The total dosage is shown in the table.
2.3 Spawning effect: Females and males are paired by 1:1 and spawned in a small water body of about 1 to 0.5 m2. When the water temperature is 26 to 30°C, the effect time is 30 to 36 hours. The spawning results are shown in the following table.
2.4 Incubation results: We use the "hydrostatic method" for hatching. Eggs collected within 4 hours of the spawning period were placed in a concrete tank. Concrete pool 15m2, water depth 25 to 30 centimeters. Do not stir the water until the fish is out of film after the eggs are laid. When the water temperature is around 30°C, the fry can be hatched in about 36 hours. Ovulation density of 2 to 30,000 particles / m3, dissolved oxygen 5mg / L or more.
3 Seed cultivation
3.1 Fish seedlings: After 3 days of hatching, the yolk sac of the fish has been absorbed, and when the fish is able to swim flat, the pond will grow. The pond size is 15m2. Three days before the fish is released, the pond is ready to be prepared when the fish hatch. The whole pool of 10mg/L bleaching powder was disinfected and cleaned, and the old water was drained and poured into new water with a depth of 30 cm. The temperature difference between the hatching pond and the hair pond pool is <2°C, and the seedling density is 2000 tails/m2.
3.2 Open bait: The first two days after the pond is sifted and squeezed with a 60-mesh sieve to produce the egg yolk slurry. On the third day, the egg yolk and agar compound were fed. The formulation of the formula is: water 4000g, egg yolk 10, fishmeal 275g, bean cake powder 25g, cottonseed cake powder 25g, agar 50g, gelatin 10g, yeast powder 25g, multi-dimensional pigment 1g, mineral additives 5g (for reference). The preparation method is as follows: cooked egg yolk is squeezed into pulp in 4000g of water, put into fishmeal, bean cake powder, cotton cake powder, stir well, boiled on the fire for 2 minutes, then add the watered agar, gelatin, and boil again. The stirring is continued until the temperature is reduced to 40-50°C, yeast powder, multi-dimensional pigments, and mineral additives are added. After stirring, the mixture is allowed to stand for 4 hours to be gelled. Appropriate amount of jelly-like compound is used for feeding, which can be fed by squeezing and filtering with a 50-60 mesh sieve in a bowl or bucket containing 3 to 5 kg of water. 4000g of water formulated material can feed 30,000 fish seedlings for two days. Daily injection 3 to 4 times, even feed for a week can start feeding small zooplankton. It is also fed 3 to 4 times a day.
3.3 The fry body length of 1.5 to 3 cm feeding: The order of feeding of the fry at this stage is: self-made formula (particle size 40-50 mesh sieve sieve). Small zooplankton, large zooplankton, fresh fish paste. The principle of feeding a small amount of fish paste is a few times.
3.4 Feeding method of fry body length of more than 3 cm: When fish fry 3 cm long, fish training begins to eat. When it has adapted to eat fish, gradually increase the fish's particle size. In other words, a bait station is set up from a fish-meat slurry fed to a masher stirred by a meat grinder. When feeding fish pieces, yeast powder and multi-dimensional additives are properly blended. The purpose is to let the bait contain all the nutrients more comprehensive and promote rapid growth of fry. Otherwise susceptible to nutritional deficiencies have died. The symptom is that the fish body is dark in color, its head is large and small, and the trunk is curved into a curve, swimming is slow, and soon it dies.
3.5 Seed screening: T. sinensis is a carnivorous fish. In the seedling stage, when the body length appears disparate and differentiated, the larger fish in the school can retire the fish whose body length is less than 1/3. Persimmons affect the survival rate of seedlings. In order to ensure a high survival rate, when there is a significant difference in body length among the fish groups, they should be screened immediately and the small fish ponds should be cultivated. This work is particularly important in the cultivation of carnivorous fish stocks and must be negligent.
3.6 Water Quality Management: Seedlings are cultivated under high density conditions in the cement pool. Fish excrement and residual bait are most likely to pollute the water quality, and the self-purification capability of the cement pool is poor. Therefore, during the breeding process, it is necessary to constantly change the water. Every 2 to 3 days, it is necessary to change the water once. The sediment at the bottom of the pool should be completely drained to keep the water in the pool fresh. Dissolved oxygen is maintained above 5 mg/L, and pH between 8 and 9 is appropriate.
4 Fish Disease Prevention and Control According to our experience, there are trichodiasis and echinococcosis in the seedlings of T. sinensis during the cultivation process. Here's how we treat these two diseases.
4.1 Trichodinosis: Fish suffering from trichomonadosis are dark when in severe condition, and are isolated and unresponsive. The surface of the fish body, especially the fins, is covered with active parasites and the worms are also attacked by trichoderma. To cure this disease, we used 0.710-6 copper sulfate and ferrous sulfate mixture (5:2). After the first medication, combined with water changes, all pool water is drained, and the shed body is also discharged outside the pool with the drained water. Then add new water. It can be cured after 2 consecutive times.
4.2 Scab Ichthyosis: Scrap Ichthyosis is a more difficult fish disease. With a single drug alone, it can do nothing about it. We have tried and concluded a comprehensive treatment. This method is the first day of Quanchiposa 0.2-0.310-6 malachite green. 8-12 hours after application, drain the pool water, sweep the bottom of the pool, and add new water; the next day, Quanchiposa 2.510-6 copper sulfate. 8-12 hours after application, then drain the pool water and add fresh water. On the third day, the whole pool is splashed with 30 to 4010-6 hot pepper powder and ginger powder mixture (1:1), and the mixture will be boiled into soup. Juice splashed with slag. About 12 hours after application, the pool water was drained and fresh water was added. On the 4th day, the whole pool was splashed with lime water of 30-4010-6. On the fifth day, all the fish were observed to be shedding. The fish eats normally and swims lively, indicating that it has been cured. The treatment of this disease has been reported in detail in the 11th issue of the 99th issue of this issue.
5 Discussion and Conclusion
5.1 The survival rate of each batch of seedlings differs greatly. There are two main reasons: one is bait and the other is disease. In the case of feeding artificially formulated feeds and fish, if the amount of natural foods can be matched, the survival rate is high. Such as the first batch, otherwise it is low, such as the third and fourth batches. Therefore, the full-price artificial feed requires further research and development. The self-purification capability of the cement pool is poor, so changing the water, disinfecting, preventing disease, and preventing the mutual flow of water in each pool are instantaneous. Disinfection after the tool is used is an important means for disease prevention.
5.2 Scab Ichthyosis is a disease that is extremely harmful in the cultivation of Chinese wolfberry seedlings. It can be completely destroyed by a single accident. After we passed the sample test, we took a comprehensive treatment to cure the disease. Early detection and early treatment of the disease will minimize the mortality rate.
5.3 When the seedlings of T. sinensis are propagated in a controlled greenhouse, the temperature for oxytocin production and incubation can be controlled between 25 and 30°C. The temperature of the outdoor pond in the northern Xinjiang in May and June in Xinjiang is not up to such a high temperature. Generally, it can only reach 18 to 22°C. In this experiment, we conducted a relatively late and later we can advance to early April. It takes 30 to 40 days for the seedlings to grow to 6-8 cm in the greenhouse. At the beginning of April, the oyster production was started. When the fry grows up to 8 cm long in mid-May, the temperature of the outdoor pond can rise to about 20°C. After the fry is gradually cooled in the greenhouse, the fry can be moved to an outdoor pond for cultivation. At this time, the aquatic insects and wild fishes in the pond are also in a large breeding season. After the Wuchang seedlings are put into ponds, they have a wealth of natural live bait, which is very favorable to the cultivation of black locust.
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