Culture techniques of Pengze crucian carp

Pengze crucian carp, also known as Luhua crucian carp, belongs to Carassius auratus, which originated in Pengze County, Jiangxi Province. Pengze crucian carp has the advantages of large individual, fast growth rate, miscellaneous food habits, strong stress resistance, less disease, fresh and tender meat, high nutritional value, etc., coupled with simple feeding technology, convenient management, low investment and good benefits, so it is deeply welcomed by farmers and consumers. 1. Ecological habits 1. Morphological characteristics: Pengze crucian carp has a spindle shape, a small head, a thick back, a gray-black back, a gray-white abdomen, a bluish-black fin, and a gentle arc from the bottom of the mandible to the bottom of the pectoral fin. 2. Living habits: Pengze crucian carp is a wide-temperature fish and likes benthic life. The main growing season is from April to November, of which July to September is the fastest. Pengze crucian carp can adapt to a wide range of water temperature, the water temperature is about 4 ℃, more than 80% of the fish will eat a small amount, even in the frozen water can still live a good life. The optimum growth temperature of Pengze crucian carp is 2530 ℃, and the survival of Pengze crucian carp is not affected by the water temperature as high as 38 ℃. Pengze crucian carp is a large crucian carp, common individuals in more than 250 grams, after 8 months of growth weight can reach more than 100 grams 150 grams. 3. Breeding habits: Pengze crucian carp can lay eggs not only in rivers and lakes, but also in still water ponds. The gonads of Pengze crucian carp bred in spring or summer can develop to the Ⅳ stage at the end of autumn. Under natural conditions, Pengze crucian carp belongs to the type of multiple spawning, and the breeding season is from March to July. The spring water temperature rises to 17 ℃ and begins to spawn and reproduce, and the water temperature is 20: 25 ℃. The fertilized eggs can hatch fish fry after 53 hours at the water temperature of 18-20 ℃. The higher the water temperature is, the shorter the hatching time is. The time from hatching to swimming of fish fry is roughly the same as that of hatching. Second, breeding technology 1, the source and cultivation of parent fish. The parent fish of Pengze crucian carp comes from 1-year-old and 2-year-old adults cultured in adult ponds or seedling ponds. The selected parent fish require more than 200 grams for females and more than 150 grams for males, in line with morphological standards, strong physique, disease-free and injury-free. The selected parent fish should be cultivated in a special pond to survive the winter. the overwintering pond requires leeward and sunny, with an area of about 1 mu and a water depth of about 2 meters. If the weather is fine during the overwintering period, concentrate feed should be fed according to about 2% of the body weight of the fish, and the male and female parent fish should be cultivated in separate ponds in time after the beginning of spring. After dividing the pond, the management should be strengthened, the feeding quantity should be increased appropriately, the pond should be inspected frequently, and the changes of water temperature and water quality should be paid attention to. 2. Identification of male and female fish. The male and female identification of Pengze crucian carp shows that in the non-reproductive season, the tip of the pectoral fin is long, and the end reaches the base of the ventral fin is the male, but not the female. In addition to the reproductive season, there are other identification methods: the female body surface is smooth and soft, the figure is plump, the outline of the ovary is obvious, and the eggs can often be extruded from the lower abdomen. Male individuals have chasing stars on the head and pectoral fins, the body surface feels rough, the abdomen is shrunken, and milky white fluid flows out of the abdomen under light pressure. 3. Preparation before labor induction. The pond of 0.6 mu is selected as the spawning pond of parent fish. The spawning pond should be cleaned and disinfected 8-10 days before spawning, and then water injection should be about 70 cm. The fish nest is made of palm bark or willow root. soak and disinfect the fish nest with 10-20 parts per million potassium permanganate or 1 ram 5000 malachite solution before use. dry and set aside. The commonly used agents are chorionic gonadotropin (HCG), luteinizing hormone-releasing hormone analogue (LRH-A), fish pituitary (PG) and so on. 4. Artificial induced labor. When the water temperature rises to 17 ℃, you can choose sunny weather for artificial labor. To induce labor, the selected male and female parent fish were matched according to the ratio of 3 ∶ 1, and one interbasal injection of pectoral fin was used to induce labor. The injection dose is generally HCG 800000 IU / kg female fish weight, or LRH-A 20mg / kg 30 μ g / kg, or PG 2kg / kg. Other drugs are used to induce parturition according to the instructions, and the injection dose of male fish is halved. The above drugs can be used alone or mixed with more than two kinds of drugs, and the effect is better. The best time for injection is 3: 00 p.m. to 5 p.m., so that the parent fish can lay eggs the next morning. The fish nest should be put away in the evening of the day of injection. 5. Hatching. The water temperature is 18: 20 ℃, the spawning time is 9: 16 hours, the spawning process of the whole population lasts 6-20 hours, the chase of parent fish in estrus is often below the surface of the water, and the sound of water waves and slamming is small. Pengze crucian carp will eat fish eggs after spawning, so the nests full of fertilized eggs should be moved to the incubator to hatch in time after spawning. The suitable area of the hatching pond is about 1 mu, and the water depth is about  0.6m. The pond should be cleaned and disinfected beforehand, and fresh water should be injected. Generally, 20 ~ 300000 fertilized eggs are released per mu, and the water temperature is 1820 ℃. The fish fry can be hatched in about 50 ~ 55 hours, and the fish nest can be removed 3-4 days after emergence. Seedling cultivation Pengze crucian carp seedling cultivation can be divided into summer flower cultivation and winter slice cultivation. 1. Summer flower cultivation. The stocking amount of fish fry per mu is generally 15 ~ 200000, and the emergence rate of 80% of the fertilized eggs can be roughly estimated. When the fry begins to emerge, some fermented organic fertilizer can be applied in the pond to cultivate the water quality, so that when the fry begins to eat, there are a large number of rotifers and other phytoplankton in the pond as palatable bait for the fry. Feed cooked egg yolk or soybean milk in time 2-3 days after emergence. After 4-5 days of emergence, the fry was fed twice a day and sprinkled around. Generally, 1.5-2.5kg soybeans were used for every 100000 fry per day. With the growth of fry, the amount of bait and fertilizer was gradually increased, from being sprinkled around to sprinkling in the whole pond. Summer flower cultivation stage 5-7 days to add new water once, add water 10-15 cm. After 20-30 days of cultivation, the fry can grow to about 3 centimeters, which can be divided into ponds or sold. Two net-pulling exercises should be carried out before dividing the pond or selling. Now most of the summer flower fry are cultured directly in the pond, and the commercial specifications can be reached in that year, so the summer flower cultivation can adopt the method of sparse culture and quick growth, with 8 ~ 100000 fish fry per mu. The specification of such summer flower fry out of the pond is neat and the survival rate is high. And the time to get out of the pond can be about 10 days in advance. 2. Cultivation of winter slices. When the summer flowers are cultivated to about 3 cm, the fry can be transferred to the cultivation stage of winter slices. The fish fry pond should be cleared and disinfected one week before going into the pond. the fish fry pond should cover an area of 1 million mu, with 20 000 to 30 000 summer fry per mu, and 1 000 fish fry of silver carp and bighead carp. The cultivation of winter fillet fish is mainly fed with feed, supplemented by fertilization, and the daily management is similar to that of other domestic fish. The growth of fish species should be checked frequently in the middle of cultivation. The weather turns cold and the water temperature drops, but the pond can survive the winter. There are 40 ~ 50 000 fish species per mu in overwintering ponds. During the overwintering period, the fine feed should be fed properly when the weather is fine, so as to ensure the physical fitness of fish species and improve the survival rate. Fourth, adult fish culture Pengze crucian carp adult fish culture, mostly in the form of mixed culture. 1. Culturing in grass and silver carp breeding ponds. Under the condition of not reducing the stocking amount of grass and silver carp summer flower fingerling, 150 and 200 Pengze crucian carp summer flower fingerlings were reared per mu. Under normal feeding and management conditions, the starting catch size of Pengze crucian carp can reach 200 grams, the largest individual can reach 310 grams, and the income of adult Pengze crucian carp can be increased by 20 kilograms per mu after raising from May to June. 2. Culture in adult ponds such as grass, silver carp, bighead carp and carp. It is an effective measure to increase production by putting Pengze crucian carp summer flower fry into adults directly in adult ponds. There are 200 fish species per mu of 3 cm. After 6 months of breeding, the average specification can reach 180 grams, and does not affect the stocking of other fish. 3. The pond is mainly raised. 1 500 Pengze crucian carp winter fillet fingerlings were released per mu, and 600 to 700 grass, silver carp and bighead carp were raised, mainly to feed concentrate fodder. After 5-6 months of feeding, about 300 kg of Pengze crucian carp and 150 kg of grass, silver carp and bighead carp could be harvested. There are 2000 Pengze crucian carp summer fry per mu, and the size of Pengze crucian carp can reach 100g to 150g at the beginning of fishing. 4. Cage culture. A floating cage of 16 square meters and 200 Pengze crucian carps with more than 5 centimeters per square meter were selected and fed with pellet feed for raising carp 4 times a day. It can grow to 100 grams in 100 days and 250 grams in 200 days. Pengze crucian carp is also suitable for breeding in parent fish ponds, mixed culture in small lakes and reservoirs, or stocking in rice fields. 5. Disease and its control Pengze crucian carp, as an artificially selected new breed, has strong disease resistance and is one of its main excellent characters. In many years of aquaculture experiments and large-scale (tens of thousands of mu) aquaculture production, there has not been a case of mass death of Pengze crucian carp due to some kind of fish disease, nor has there been an explosive fish disease. Practice has proved that Pengze crucian carp has a very low infection rate of various diseases, even if infected with diseases, the survival rate will not be greatly affected, only affecting the growth rate or appearance of diseased fish. The common diseases of Pengze crucian carp are fish diseases caused by surface animal pathogens, such as water mildew and Gill rot. 1. Gill rot disease: Gill rot disease occurred in Pengze crucian carp cultured in cage. The sick fish move slowly, the body color is black, and often wander alone on the water surface. The inner epidermis of the Gill cover of the diseased fish is corroded into a round transparent area, commonly known as "open skylight". The ends of the Gill filaments are white and rotten, adhered to by floating mud, and the masses are called "dragging mud". In serious cases, the Gill cartilage is exposed, resulting in death due to difficulty breathing. The pathogen is fish myxococcus, and the epidemic season is from May to September. The disease can cause sporadic death of Pengze crucian carp. Prevention and treatment: insist on hanging baskets with bleach or salt during the season or during the onset of the disease. After treatment, the disease will be effective in about a week. 2. Water mildew. Water mildew only occurred in the hatching stage and fry stage of Pengze crucian carp fertilized eggs. The pathogens are Streptomyces, Rhizoctonia, Cysticercus and Trichoderma in the family Streptomyces. The popular season is from March to May. In the process of fish egg hatching, Pengze crucian carp eggs are seriously damaged by water mildew due to the relationship of climate and water temperature. When the fish eggs are infected with mold, the hyphae invade the egg membrane like roots, and the hyphae grow outside the egg membrane, resulting in the death of a large number of fish eggs. In the fry stage, mold invades the wound due to careless operation during cuttage and handling, scrubbing off scales, or parasites destroying the skin. When visible to the naked eye, the hyphae have gone deep into the muscles, spread and expanded, growing outward into cotton-like hyphae, so it is called "raw hair". Diseased fish are characterized by overburdened fish floating on the water, abnormal swimming, loss of appetite and finally emaciation and death. Prevention and treatment: thorough cleaning and disinfection (preferably quicklime) can effectively prevent water mildew. In the hatching stage of fish fry, it is more important to choose the appropriate climate and water temperature to induce reproduction. For Pengze crucian carp, we must pay attention to avoid cold wave and cloudy and rainy weather. Generally, we should choose the water temperature of 17 ℃, and it is expected that there will be 4-5 sunny and warm days after labor. In addition, fish nests should be set up more so that the fish eggs are not too dense, which can effectively prevent or reduce the occurrence and harm of water mildew. 3. Rotifer disease. Rotifer mainly occurs in the breeding stage of Pengze crucian carp summer flower fish. The epidemic season is from May to August and the peak is from June to July. The pathogen is rotifer. After the body surface or Gill of diseased fish is stimulated by pathogens, a large amount of mucus is secreted, and the tissue is seriously damaged. Diseased fish lose weight, swim slowly, swim laterally at intervals, have difficulty in breathing, and often swim at the edge of the pool, which can cause a large number of deaths. Generally speaking, this disease is most likely to occur in fish ponds with small area, shallow water and high stocking density. Prevention and cure method: sprinkle the whole pool with the mixture of copper sulfate and ferrous sulfate (the proportion is 5 ∶ 2) to make the pool water at a concentration of 0.7 parts per million. Or copper sulfate was used alone, and the best application method was the secondary method. The first application made the pool water reach a concentration of 0.4 ~ 0.5 ppm, and three days later, the second application made the pond water reach a concentration of 0.3 ppm. Generally, it can be effective 3 days after application. 4. Fish carp disease. The disease occurs in Pengze crucian carp winter fillet breeding stage and adult fish culture stage, and can be infected all the year round. The pathogen is fish fish. The symptoms of the diseased fish are extremely restless, swimming violently and jumping sideways, and the fish body is visible to the naked eye. Fish fish disease generally does not cause the death of Pengze crucian carp, but it will seriously affect the growth of Pengze crucian carp. Prevention and control methods: at the beginning of the epidemic, crystal trichlorfon was sprinkled in the whole pond once, and the concentration was 0.25 ~ 0.5 parts per ten thousand. 5. Anchor head scrofula disease only appeared in the adult stage of Pengze crucian carp, and the onset season was from April to October. Pathogens are a variety of anchor heads, parasitic on the body surface or oral cavity of fish (very few). Anchor head disease generally does not kill Pengze crucian carp. In the early stage of the disease, the diseased fish showed restlessness, intermittent lateral swimming, loss of appetite and weight loss, which seriously hindered the growth of the fish. The anchor head is drilled under the host muscle or scale with its head horn, causing redness, swelling or necrosis of the surrounding tissue, and a small number of diseased fish will be infected with water mildew at the same time, resulting in death. Prevention and control methods: in the disease season, crystal trichlorfon was sprayed all over the pond with a concentration of 0.2 ~ 0.3 per ten thousand, once every semimonthly for 2 consecutive 3 times. Treatment: sprinkle the whole pool with crystal trichlorfon, make the pond water at a concentration of 0.5 ppm, use it again after a week, or rinse the fish with 0.025 ppm potassium permanganate solution for 20 minutes.