Culture technology of black carp

Herring is bluish, which is one of the "four major domestic fish" in freshwater culture in China, mainly distributed in the plain area south of the Yangtze River in China. Herring has the advantages of large individual, simple feeding, rapid growth and broad prospect of artificial feeding. This issue introduces a group of herring culture techniques for farmers' reference.

1. Maintain the water body to ensure the growth environment

The fish species should be released around the end of February, so the water temperature is low, the fish scales are tight, and the fish species are not easy to be injured by pulling the net, handling and so on. A total of 250 two-year-old green fish with a tail weight of 1 kg per mu, 100 silver carp, 50 bighead carp and 20 snakehead fish with a tail weight of 0.3 kg were released per mu. Before entering the pond, the fish were soaked in a mixture of 8 grams of copper sulfate and 1 gram of bleach for 20 minutes for 30 minutes, or disinfected with 3%-5% salt water for 15 minutes.

Herring fingerling should choose more than 6-year-old herring species weighing more than 15 kg, physically strong, no damage, male and female according to 1:1 ratio of herring species for storage. The storage pond has an area of 370 mu, a water depth of more than 2 meters, a flat bottom and loam soil, with 1-2 herring per mu. A month before spawning, the herring was concentrated in a special pond for cultivation.

Herring species are mainly fed with fresh snails and clam meat, supplemented with a small amount of vegetable cake and bean cake bait, flushing regularly, usually once a month in winter, 5-7 days a month after the beginning of spring, and every 3-5 days before parturition, in order to promote the gonadal development of green fish. Usually, the pool water should be kept clean after mixed culture, and fresh water should be injected regularly so that the water quality can meet the requirements of "fertilizer, live, tender and cool". In spring and autumn, water is injected 2 times a month, 5 times a month in summer, 8 cm each time, and quicklime is sprinkled once every 15 days in June (15kg / mu). In spring and autumn, the water is generally changed once a season, and in summer, the water is changed once a month, and the amount of water changed each time is 1 pound of the original pool water. The cover can be removed directly when changing water, because the herring is a lower layer fish, so the fish body will not escape during drainage, and should be installed immediately after the end of drainage.

Patrol the pond every night, observe in the middle of the night on cloudy and rainy days and turn on the aerator at the right time. Generally from June to September, the aerator is open for 1-2 hours at noon on a sunny day. When the floating head is heavy, it must be turned on until dawn. When the weather is colder, it is not necessary to open the aerator every day.

two。 Artificial spawning to improve the breeding ability of parent fish

The first mature age of Yangtze River herring is 3-6 years old, usually 4-5 years old, and the male fish is 1-2 years earlier. The mature female fish is generally about 1 meter long and weighs about 15 kilograms. Mature male fish are generally about 900 mm long and weigh about 11 kg. The breeding season is from May to July, and the general rise of river water can stimulate its spawning. The spawning activity is scattered and lasts for a long time. The spawning ground is distributed in the section of the Yangtze River from Chongqing to the Taoist Shibai River, and there are also tributaries in Hanshui and Xiangjiang River, but the scale is small. The average absolute number of eggs per kilogram of body weight is 100000, and the maturity coefficient is about 14%. About 50, 000 eggs can be obtained per kilogram of body weight. The egg is drifting, the egg membrane is transparent, the egg diameter is 1.5-1.7 mm, and it can reach 5-7 mm after water absorption and expansion. Spermatozoa generally have the ability to fertilize within 1 minute after being discharged into fresh water. The optimum temperature for embryo development is 18 ℃ ~ 30 ℃, and the optimum temperature is 26 ℃ ±1 ℃. When the temperature is lower than 17 ℃ or higher than 30 ℃, it will cause developmental stagnation or malformation. The larvae were hatched in about 35 hours when the water temperature was 21 ℃ ~ 24 ℃. The newly hatched larvae are yellowish, 6.4-7.4 mm long and slightly curved. After the disappearance of the yolk sac and the appearance of the swim bladder, the head and back of the herring fry showed a black pattern. During reproduction, pearls appear in the inner pectoral fin, operculum and head of male fish, while the pectoral fin of female fish is smooth and without pearl star.

The time of induced labor is generally in the middle and last ten days of May, the water temperature is 22 ℃ ~ 30 ℃, and the most suitable water temperature is 25 ℃.

Herring maturity selection of herring maturity directly affects the effect of induced spawning. herring should be strictly selected when it is used to induce spawning. the selection standard of male fish is that there is semen flowing out of the reproductive pores in the abdomen, which can be dispersed after warm water, and the abdomen of female fish is inflated, soft and elastic, and the abdominal scales are sparse.

The use of oxytocin commonly used herring induction drugs are "PG", pituitary, "LRH-A' luteinizing hormone releasing hormone analogues," HCG' chorionic gonadotropin, GTH gonadotropin, "DOM" dione and other oxygenating agents, usually heavy floating head must be turned on to dawn, when the climate is colder, do not have to turn on the aerator every day.

3. Scientific incubation ensures reproductive benefit

After injecting the second injection of spawning agent into estrus, put the herring species back into the spawning pool, and wait for the effective time to carry out artificial egg collection and insemination in time when the herring is in estrus. The benefit time varies with the water temperature, the water temperature is 25 ℃ ~ 28 ℃, and the benefit time is 8: 10 hours. At this time, the dynamics of the herring estrus should be carefully observed. As soon as the time for oestrus arrives, catch the herring and install the herring with a fish pole for inspection. At this time, if the female fish gently press the abdomen, the eggs can flow out of the reproductive pores, and the males can squeeze out the semen and warm water to spread quickly, they can start artificial egg harvesting.

Collect semen for dry water artificial insemination, if the natural sperm eggs cannot be collected, put the herring species back into the spawning pool and wait for the herring to be in estrus. The collected eggs and sperm should be fully mixed to fertilize and avoid direct sunlight to kill the eggs during artificial insemination. After insemination, fertilized eggs should be quickly diluted with water and put into the loop to hatch. Tools, washbasins, nets, fish beds, bristles and so on should be prepared before artificial insemination. The personnel coordinate and cooperate to make the action brisk, so as to avoid the injury of the green fish.

The fertilized eggs collected artificially by loop hatching should be hatched in the loop water prepared in advance in time, with a density of no more than 1.2 million eggs per square meter. The flow rate in the loop should be appropriate. In the early stage, the flow rate of water is about 17 cm per second, and the expanded fertilized egg rushes and rolls to the surface. When the fry just came out of the film, the management of the mixture of three drugs and four drugs should be strengthened to induce delivery, and the second injection method should be adopted. The female was injected with LRH-A2~5 mg / kg for the first injection, and the injection distance was 8 hours. The second injection was given at the dose of LRH-A10~20 mg + PO2~4 mg + HCE500~1200 International Unit or plus DOM5 mg, and the mixture was prepared into a mixture. The male fish was injected intraperitoneally. The effect time was 8 to 10 hours.

4. Prevent in advance and reduce the occurrence of epidemic disease

The prevention and control of epidemic diseases adhere to the principle of "giving priority to prevention, prevention is more important than control, and the combination of prevention and control". The fish species were strictly disinfected before stocking, and sprinkled with 1 gram of crystal trichlorfon per cubic meter after the pond, followed by regular disinfection with 25 ml of quicklime and 1 ml of bleach, and regular administration of drugs to prevent enteritis. The bait is fresh and palatable, and the dead fish are fished out of the deep soil in time, and the fishing gear used should be washed and disinfected. The chlorine-containing preparation was sprinkled and disinfected in the whole pool, and the medicine was added to the bait to make the bait. Herring is extremely sensitive to drugs, a little inattention in the treatment will bring harm to the fish, fish medicine should be used in strict accordance with the regulations.

Bacterial enteritis is very easy to occur under the condition of high density culture, and the onset period is mostly from April to September. If you want to treat the disease in time, you can usually fish the diseased fish out of the water first to avoid affecting other fish, and then sprinkle 100 times of bleach into the pond, or you can use 100 times of crystal trichlorfon, 100 kg per mu, and internal medicine. 40 grams of neomycin sulfate powder can be added to every 100 kg feed, which can be fed once a day and used 2 times in a row.