Catfish artificial propagation technology

Carp is a general name for carps, and it is a kind of small and medium-sized edible fish that is commonly distributed in rivers, lakes and reservoirs in China. It mainly consists of larvae, maggots, yellow-tailed catfish, and silver carp. Their common feature is to make full use of organic debris and epiphytic algae in the waters. Mackerel adaptability, fast growth, easy to catch. Its high meat content (viscera only 8% to 12% of body weight), tender and delicious meat, nutritious, favored by consumers. However, in recent years, wild salmon resources have been severely damaged, resulting in a shortage of supply in the market and rising prices. Therefore, it is of great significance to study and summarize the artificial propagation technology of squid, and then to develop larval rearing and adult culture. The artificial breeding techniques of squid are introduced as follows:
First, the choice of broodstock can be carried out in the early winter in the winter or the following year. It requires strong physique, no disease or injury, and more than 2 years of age. Silver brood broodstock weighs more than 100 grams, yellow pheasant bream and ribeye brood broodstock weighs more than 500 grams, round brood broodstock weighs more than 600 grams. This type of fish ovulation volume is about 100,000 tablets. Generally mature but smaller individuals have poor egg mass resulting in low fertilization rates and low hatching rates.
Second, broodstock breeding broodstock can be single, polyculture. Single-cultivation is about 300 stocks per mu, and polyculture is about 1 million stocks per mu. The broodstock breeding pool will release 50 kilograms of fermented manure per acre every day after the beginning of spring so that the transparency of the pool water will be maintained between 25 cm and 30 cm. Each day, 8 grams to 10 grams of soybean milk and bran are fed. Flush once every half a month to keep the water fat, tender and cool. The carp is impatient, and in order to adapt to the artificial breeding operation and to reduce the death, each year in the autumn and spring, the net should be exercised several times regularly. After training, the broodstock will not cause frightened jumps and injuries when pulling the net during production.
Third, male and female identification in the non-breeding season can be identified with the naked eye, the male head, skull cover, pectoral fins and Scales appear on the white star, the body surface is rougher than the female fish, gently pressing the abdomen can squeeze milky white semen. Females have enlarged abdomen, obvious contours of the ovaries, and soft feeling of pressure. If eggs are inspected with an egg digger, the size of the eggs is uniform and easy to separate. This is a sign of sexual maturity and can be artificially induced.
Fourth, artificial oxytocin Each year in late April to early May, when the water temperature is stable above 18 °C, artificial ovulation can be carried out. Appropriate production water temperature 18 °C ~ 27 °C, the optimum water temperature 20 °C ~ 25 °C. When the water temperature is above 28°C, the fertilization rate and hatching rate will be reduced, and the broodstock mortality rate will be high. Of the commonly used oxytocin drugs, the PG of carp had the best effect. One injection method was used for intrapleural injection. The dose of female fish was PG 2 mg/kg ~ 3 mg/kg, and the male fish was halved. After the injection, the broodstock is placed in the spawning pool at a female and male ratio of 1:2, allowing it to naturally spawn and fertilize. Under the condition of water temperature of 18°C~20°C, spawning takes place from 10 hours to 12 hours; at water temperature 21°C~24°C, spawning takes place from 10 hours to 12 hours; water temperature is 21°C~24°C and spawning takes place at 9 hours; water temperature is 25 °C ~ 27 °C, 6 hours to 8 hours spawning. Once the broodstock estrus has been found, one kilogram of yellow slurry water (10 kg of water plus 1 kg of yellow mud) is splashed in every cubic meter of water in time to de-bond it. Fresh water was continuously added after 20 minutes to 30 minutes to collect fertilized eggs. The deferred fertilized eggs can be transferred into the hatching tank or loop water to hatch.
Fifth, artificial incubation Each cubic meter of water placed 700,000 to 800,000 grains of fertilized eggs, the first bath with methylene blue solution for 8 minutes to 10 minutes to prevent mildew. Then open the inlet valve and run the water hatch. Due to the small size of the fertilized eggs and their artificial detackification, the surface of the carp is accompanied by sediments and a large proportion of eggs. Therefore, the speed of the water flow during hatching is required to be large, and it is appropriate to see the fertilized eggs move up and down with the water. Water for hatching must be filtered through screens to prevent entry of predator organisms and other impurities. The suitable water temperature for hatching is 20°C~28°C, and the water temperature is higher than 30°C. Although it can hatch and emerge, it is mostly malformed. When the water temperature is lower than 15°C and the embryo develops to the primitive gut stage, it will stop. Under the condition of water temperature of 22°C-25°C, the fertilized eggs can be released from the shoots after about 40 hours. Freshly hatched juveniles are smaller and tenderer than the fry, and have no swimming ability. They can only float up and down with the water. When the juveniles are paralyzed and can swim flat, the water flow rate needs to be reduced to reduce the juveniles' physical energy consumption. After 3 to 4 days of release, when the guts and throats of the juveniles are connected and they can take the initiative to feed, fry can be cultivated in the lower pool.

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