Bluefish, also known as blue carp, snail green, black carp, steel blue, is one of the four major fish in China, belongs to the cyprinid family Yaro fish subfamily. The body is cylindrical, the tail side is flattened, the abdomen is round, the back and upper part of the body are blue-black, the abdomen is milky white, and each fin is gray-black. It is a benthic carnivorous fish, and the juvenile fish mainly feed on zooplankton, mosquito larvae and arthropods; in the adult stage, they like to eat snails, mussels, small fish, small shrimp and aquatic insects. Under artificial culture conditions, a variety of compound feeds can be fed.
Bluefish is large, thick, fatty, delicious, less intermuscular spines, rich in nutrients, 19.5 grams of protein and 5.2 grams of fat per 100 grams of meat, and contains a lot of vitamins and zinc. It is the best quality of freshwater fish, the best meat quality in the four major fish, the economic value is very high, and the pollution-free breeding of bluefish has broad prospects for development.
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First, the breeding environment requirements
The breeding environment includes the atmospheric environment, the aquatic environment of fish growth and the water quality of fishery water sources, etc. The breeding environment must comply with the provisions of the national standard "Safety and Quality of Agricultural Products and Environmental Requirements for Pollution-free Aquatic Products" (GB/T184074-2001), "Fishery Water Quality Standard" (GB/T11607-89), "Pollution-free Food Freshwater Aquaculture Water Quality" (NY5051-2001).
1. Selection of aquaculture waters
The waters for bluefish aquaculture should be selected in waters with good ecological environment, sufficient water sources, and no or no direct pollution by industrial wastes and agricultural, urban life and medical wastes. There are no sources of pollution in the aquaculture waters and upstream of the upwind direction and irrigation water sources that pose a threat to the aquaculture water environment.
2. Remove excess silt from ponds
Silt is composed of biological carcasses, residual bait, feces, various organic detritus, and various organic and soil deposits. Through the decomposition and ion exchange of bacteria, they are continuously dissolved and released into the water, providing nutrients for the reproduction of bait organisms. However, too much silt will produce a large amount of hydrogen sulfide, methane, organic acids, low-grade amines and thiols, etc., which accumulate in the water and affect the health and growth of bluefish. Therefore, excess silt should be removed. The specific measure is to drain the pond water every one or two years of breeding, dig out too much silt, and make it more appropriate to retain about 20 cm of silt at the bottom of the pond. At the same time, expose and freeze the bottom of the pool to kill pests, parasites and pathogenic bacteria.
3. Pond water disinfection
To improve the pond environment, eliminate predators, prevent some bacterial diseases, and disinfect ponds and water bodies. Commonly used disinfectants and their dosages are as follows: (1) use a quicklime belt water clear pond with a content of 200 mg to 250 mg per liter, or sprinkle the whole pool with a content of 20 mg to 25 mg per liter of quicklime water; (2) use a bleaching powder content of 20 mg per liter to bring water to clear the pond, or use a content of 1.0 mg to 1.5 mg per liter of bleach powder water to sprinkle disinfection in the whole pool; (3) use a content of 0.3 mg to 0.6 mg per liter of sodium dichloroisocyanurate solution to sprinkle disinfection in the whole pool; or use a content of 0.2 mg per liter to disinfect the whole pool 0.5 mg of trichloroisocyanuric acid solution was sprinkled throughout the tank for disinfection.
4. Water quality management
The water environment is the basis for the life and growth of bluefish in ponds, and various fish farming measures are also acting on fish bodies through the environment. Therefore, water quality management is a bridge for pollution-free farming of bluefish. It is necessary to ensure that the pool water is rich in plankton, organic matter and nutrients; the transparency of the pool water should be maintained between 25 cm and 40 cm. The dissolved oxygen in the water is more than 4 mg, the pH value is 7 to 8.5, and the water quality meets the requirements of fertilizer, live, tender and refreshing.
Second, the cultivation of seedlings
The production and introduction of bluefish fry should comply with the provisions of China's Fisheries Law, the Quality Standards for Fingerlings of Bluefish Fry (GB9956—88) and the Measures for the Management of Aquatic Fry issued by the Ministry of Agriculture, and the parents used for breeding must come from the original fine seed farms, and the quality must conform to the standards of "Broodstock" (GB/T5055—1997). Production conditions and facilities should meet the requirements of production technology operating procedures, and the quality of seedlings must be inspected and quarantined by qualified professional and technical personnel.
1. Selection of seedlings
The advantages and disadvantages of the bluefish fry can be distinguished according to the size, body color, activity of the fry and physical strength of the pond specifications: high-quality bluefish fry should meet the "Blue fish fry quality standards", the pond specifications are neat, the body color is bright, shiny, the action is lively, and the rapid diving into the water after being frightened has a strong ability to grab food. When the sample was carried out, the seedlings jumped wildly in the white porcelain pot, the body was fat, the fins were intact, and there was no abnormality. On the contrary, inferior seedlings.
2. Cultivation of seedlings
According to the different requirements of the bait of the bluefish fry at different stages of development, it can be divided into two stages for cultivation. (1) Fry stage. The spray is released for 3 to 5 days, the stocking density is 1 million to 1.5 million per hectare, and the pond area is 1334 square meters to 2668 square meters. Soybean milk is fed on the first to 10th day after the pond, of which 30 kg per hectare for the first 5 days, 40 kg per hectare for the last 5 days, and increase as appropriate after 10 days, twice a day, and the whole pool is evenly sprinkled. Add 15 cm to 20 cm of water every 5 to 7 days, and add 1.3 m to 1.5 m of water depth to the summer flower pond. According to the water quality of the breeding pond, the appropriate amount of topdressing is applied. After about 25 days of breeding, the fry should be sparsely divided into ponds, and two or three intensive exercises should be carried out before leaving the pond. (2) Fingerling stage. The diet gradually differentiated, and began to feed on small snails. The stocking time is before the summer solstice, the area is 2000 square meters to 4000 square meters, the water depth is 1.5 meters to 2 meters, the bluefish are placed 80,000 to 100,000 fish per hectare, the bighead carp is put 18,000 to 20,000 fish per hectare, and the crucian carp is placed 0.5 million fish per hectare. First use a small amount of concentrate to lure the bluefish to the food table, and then feed the soybean cake paste twice a day, each time feeding 2 or 3 kg per 10,000 tails; mixed vegetable cake after the specification of 5 cm, 7 cm after changing to soaked vegetable cake or bean cake; 10 cm after the size of the mixed cast crushed snail clams, began to feed 30 kg per 10,000 tails, and then gradually increased.
Bait should be implemented in four sets. Fixed point: feeding at the food table or food field; Timing: 2 times a day, 8:00 a.m. to 9:00 a.m., 2:00 p.m. to 3:00 p.m.; Sizing: giving high-quality fresh bait according to different growth stages; Quantitative: Each feeding is based on 1.5 hours of eating, and the proportion of monthly feeding volume to the total feeding amount is 4% in June, 15% in July, 23% in August, 25% in September, 15% in October, 10% in November, 4% in December, and 4% in January to March. The food field is frequently cleaned, disinfected and hygienic. Frequent water injection, moderate control of fertilizer, dissolved oxygen is sufficient. Visit the pond twice a day in the morning and evening, carefully observe, arrange production according to the situation, and find diseases and treat them in time.
3. Adult fish farming
1. Pond conditions
Ponds require sufficient water sources, no pollution of water quality, water depth maintained at 1.5 meters to 2.5 meters, an area of 3335 square meters to 6667 square meters, the pond is solid, no leakage and water leakage, sufficient sunlight, flat bottom of the pond, less silt. Remove too much silt from the pond before stocking, freeze and dry for several days, add 30 cm of water, then sprinkle the whole pond with 150 kg of quicklime per 667 square meters, and after filtering and filling water every two or three days, soak 50 kg of tea seed cake for one day and night and then sprinkle it. At the same time, it is required to have a power supply, and each 2000 square meters to 3335 square meters of water surface is equipped with 1 3 kW impeller aerator and 1 bait machine.
2. Fingerling stocking
Fish fingerlings should be stocked until the toxicity of the disinfectant drug disappears, and the water is filtered to prevent wild fish from mixing into the pond. Fingerlings should be stocked around the end of February, so the water temperature is low, the scales of the fish are tight, and the fingerlings such as pulling nets and carrying them are not easy to be injured. 200 to 250 second-instar fingerlings weighing 1 kg per 667 m2 were stocked, with 100 silver carp species weighing 0.3 kg, 50 bighead carp species and 20 snakehead fingerlings weighing 0.05 kg. Before entering the pond, the fingerlings are soaked with a combination of copper sulfate (8 grams per square meter) and bleach powder (1 gram per square meter) for 20 minutes to 30 minutes, or disinfected with 3% to 5% salt water for 15 minutes.
3. Feeding management
(1) Selection of feed. Feed should comply with the Regulations on the Administration of Feed and Feed Additives, the Safety Limit Standards for Fishery Compound Feed (NY5072-2002) and the industry standards for aquaculture. Aquaculture is carried out in strict accordance with the Regulations on the Quality and Safety Management of Aquaculture promulgated by the Ministry of Agriculture, and the Aquaculture Production Records form is completed. The feed requires consistent color, no odor, no mold, deterioration, agglomeration, granular, smooth surface, high degree of ripening. The feed should not be too loose, and the water stability requirement should not collapse in 20 minutes. At the same time, the nutritional value of the feed should be assessed. Different growth stages have different nutritional value requirements for feed. The protein content of the fingerling stage is generally 35% to 45%, and the protein content of the adult stage is generally 28% to 41%.
(2) Feed feeding. A baiting platform extending three or four meters to the center of the pond is built with wooden planks and bamboo planks, and the bluefish cluster is floated up to grab food in a domesticated manner, and gradually assembled to the bait platform to be fed at a fixed point with a bait machine. The daily bait rate can be implemented according to 1.5% of the weight of the fish in March, 2.0% in April, 3.0% in May, 4.5% in June, 5.5% in July, 6.5% in August, 5.0% in September, 3.0% in October, and 2.0% in November, and flexibly grasp according to water temperature, water quality, fish growth and feeding activities. Fed three or four times a day. Each feeding allows the fish to eat 70% or 80% full. Feed evenly, and the feeding duration is controlled at 30 minutes to 45 minutes.
(3) Daily management. Pond patrol: Every day, you must patrol the pond in the morning and evening, check the water quality, and observe the fish situation. Oxygenation: From June to September, the aerator is opened for one or two hours at noon on a sunny day, started in the middle of the night on a rainy day, and must be turned on until dawn when the floating head is heavy. Water quality management: regularly fill new water, water quality to meet the requirements of fertilizer, live, tender and refreshing, every 15 days to 20 days in June the whole pool is sprinkled with quicklime once (per 667 square meters of 15 kg ~ 20 kg).
Fourth, the prevention and treatment of diseases
The use of fishery drugs should comply with the national industry standards "Guidelines for the Use of Pollution-free Food and Fishery Drugs" (NY5071-2002), "Specifications for the Use of Feed Drug Additives" and "List of Veterinary Drugs and Their Compounds Prohibited for Food Animals". Aquaculture is carried out in strict accordance with the Regulations on the Quality and Safety Management of Aquaculture promulgated by the Ministry of Agriculture, and the "Aquaculture Drug Use Record" form is completed.
1. Prevention of fish diseases
At the end of April and the beginning of May and the season of frequent fish diseases from September to October, 90% of the crystalline enemy insects are sprinkled in the whole pond at a dosage of 0.5 mg per liter to prevent the killing of parasites such as anchor fleas and Chinese fleas. After 2 days, the whole tank is sprinkled once with a chlorine-containing preparation (bleach powder, dichloroisocyanuric acid, trichloroisocyanuric acid, chlorine dioxide and dibromohydantoin, etc.) to prevent secondary bacterial infection. From mid-May to the end of August, twice a month, quicklime and chlorine preparations alternately sprinkled in the whole pool to prevent the occurrence of bacterial diseases such as enteritis and rotten gills, and the quicklime content is 20 mg to 30 mg per liter.
2. Medication
Parasitic fish diseases such as wheelworms and ringworms are often parasitic in the fry and summer flower stages; racecourse disease can occur in the Wuzai stage; bluefish fingerlings are often infected with viral hemorrhagic diseases; large-sized fingerlings and one- and two-year-old adults are susceptible to bacterial enteritis, gill rot and red skin disease. Fish disease is found and immediately diagnosed and treated.
(Source: Southern Fishing Nets)