Key techniques of tilapia fry culture
Speeding up the pace of pollution-free fishery construction and improving the quality and safety level of aquatic products have become an urgent task for the development of fishery production. At the beginning of 2008, the Fisheries Bureau of Guangxi Zhuang Autonomous Region undertook the project of "pollution-free culture technology of tilapia", and the implementation effect met the requirements of the project. At present, the pollution-free culture technology of tilapia is summarized as follows:
1、 Habitat environment and pond conditions
The project is located in Wuming county science and technology demonstration base in Nanning, Guangxi. The base is located in the suburb with fresh air, beautiful environment, sufficient light and good ecological environment. There are no industrial "three wastes" and agricultural, urban living and medical waste pollution in the field and surrounding areas. The total area of the project is 1000 mu, including 450 mu of fish pond water, concentrated production scale, and groundwater as the water source for aquaculture The water quality is good and pollution-free, which conforms to the standard of fishery water quality (GB 1607-989) and the water quality of pollution-free food freshwater aquaculture.
The pond is rectangular, east-west, each area is 4-10 mu, the depth of the pond is 1.5 meters, the bottom of the pond is flat, and the thickness of sludge is 20 cm. The pond has good water retention performance. Each pond is equipped with water intake and drainage facilities, and is equipped with aerator and automatic baiting machine.
2、 Preparation before stocking
Before using the pond, the pond water should be drained, the bottom of the pond should be exposed, about 10 cm of water should be injected into the pond half a month before the fish species are released. The pond should be cleaned and disinfected with quicklime of 150kg / mu, so as to completely kill the harmful organisms, pathogenic bacteria and intermediate hosts carrying pathogens in the pond. On the third day after disinfection, chicken manure 500-600 kg / mu fertilizer water was applied to cultivate basic bait organisms in the pond water; after 5-7 days, fresh water was injected into the pond to a depth of 80 cm.
3、 Selection and stocking of fish species
All male tilapia of Jifu strain was bred in this base and bred in special pond and overwintering in greenhouse. From May 3 to May 8, 2008, fish species with strong physique and uniform specifications in the same pond were selected for stocking in the pond. The stocking specifications were 25-40g / tail. The varieties of silver carp, bighead carp, Pengze crucian carp and catfish were self bred in the farm. The fish seeds were washed with 3-4% salt water for 10-15 minutes. The stocking and harvest of fingerling.
4、 Feed feeding
All of them were fed with special formulated pellet feed for tilapia. Before June 15, the fish seed feed was fed, and after June 15, the adult fish feed was fed, and the particle size of the pellet feed was timely adjusted according to the change of fish growth specifications. Feed feeding adhere to the "four fixed" principle, and an automatic feeding machine is installed in the middle of the north side of each pond. Due to the strong ability of automatic feeding, tilapia can be put into the formal feeding management after 3-5 days of domestication. The daily feeding amount is generally 5-7% of the body weight of the fish, and can be flexibly controlled according to the fish feeding situation, weather, water quality and water temperature, and the feeding time is controlled at about 30 minutes each time.
5、 Daily management
The operation should be carried out in strict accordance with the technical specifications for the production of pollution-free aquatic products. In addition to patrol the pond frequently and observe frequently, the water quality control measures should be taken to strengthen the monitoring of physical and chemical factors and ecological factors that can cause stress reaction of cultured fish. During the whole breeding period, the pond water should be kept fat, active, tender and fresh. The transparency of the water body should be controlled at 25 ~ 30cm, the dissolved oxygen content in the pool water should be kept above 5mg / L, and the pH value should be 7.0 ~ 8.5. During the culture period, the pond was flushed with fresh water every 10-15 days, 20-30cm each time to keep the water depth of 1.5m. At the same time, 30 ppm quicklime or 1 ppm bleaching powder are sprinkled in the whole tank every half a month, and the two are used alternately to improve the water quality. Each pond is equipped with a 3kW aerator, which is started up once a day in the morning and in the afternoon for about 1.5 hours each time, so as to appropriately extend the starting time in high temperature season.
6、 Disease control
Adhere to the principle of "prevention first, prevention more important than treatment". While doing a good job in the prevention work such as thoroughly clearing the pond, flushing new water and regularly sprinkling drugs, the first is to operate carefully when the fish is put into the pool to avoid injury to the fish body, and pay attention not to feed moldy and deteriorated feed to improve the disease resistance of the fish itself; the second is to regularly feed the feed containing allicin, VC and other drugs in the epidemic season of fish diseases according to the disease regularity The tools and feed farms were disinfected with drugs. For individual diseased fish ponds, high-efficiency, low toxicity, low residue or no residue fishery medicine with production license shall be used in strict accordance with the "guidelines for the use of fishery drugs for pollution-free food". All drugs should be stopped within half a month before the fish come out of the pond.
7、 Breeding results
1. The breeding area and production project covers a total area of 130 mu, and the breeding period is 198 days from March 25 to October 10. The total yield of adult fish is 158.6t, with an average yield of 1200kg / mu, in which tilapia yield is 855kg / mu and other fish yield is 365kg / mu.
2. The total income of output value and benefit was 1.6573 million yuan, including 1.3338 million yuan of tilapia and 323500 yuan of other fish. The total expenditure was 764400 yuan, the net profit was 892800 yuan, the average profit per mu was 6868 yuan, and the input-output ratio was 1 ∶ 2.17.
3. The quality of aquatic products was tested by Nanning Municipal Bureau of quality inspection. The sensory standards and safety and health indicators of tilapia and its associated stocking fish met the requirements of "safety and quality of pollution-free aquatic products" (GB 18406.4-2001).
8、 Summary and discussion
1. The project implementation area is constructed according to the pollution-free production base, and the site and base are completely closed and free of external pollution. Aquaculture production is based on ecological fishery