Production-increasing measures through strengthened feeding management and fish disease control in home fish farming

    1. Strictly select and retain broodstock: choose natural original stock, requiring health and good gonadal development. Silver carp above 6kg, bighead carp above 10kg, black carp above 15kg, grass carp above 8kg. The annual replacement rate of broodstock is about 10%. 

Fish farming

    2. Scientifically clean and prepare fish ponds: broodstock ponds. Convenient irrigation and drainage; silver carp and bighead carp ponds should have 20cm of mud at the bottom, while black carp and grass carp ponds should contain no mud or little mud at the bottom. Area 1—5 mu, water depth about 1.5 m. Ponds should be cleaned before stocking.

 
    3. Reasonable mixed stocking: in ponds mainly stocked with silver carp, stock 3—4 bighead carp and 3—4 grass carp per mu; in ponds mainly stocked with bighead carp, stock 6-8 grass carp per mu; in ponds mainly stocked with black carp, stock 2—3 silver carp and 2—3 grass carp per mu; in ponds mainly stocked with grass carp, stock 3—5 silver carp (bighead carp) per mu. The female-to-male ratio of silver carp, bighead carp, black carp and grass carp broodstock is generally 1:1—1.5. At the same time, stock 8—10 mandarin fish and about 150 bighead carp per mu to control the breeding of wild trash fish and large plankton. 

    4. Strengthen feeding management: before stocking, apply 500—700 kg of decomposed organic fertilizer per mu to silver carp and bighead carp broodstock ponds to cultivate plankton, and then fertilize appropriately. In addition, on clear and warm days, feed soybean cake slurry to promote gonadal development. Black carp broodstock are mainly fed snails and clams, supplemented with concentrated feed such as soybean cake. Grass carp broodstock are mainly fed green grass, ryegrass, sweet potato vines, etc., supplemented with concentrated feed; if green grass is insufficient in spring and autumn, concentrated feed should be the main feed. To keep water quality fresh, irrigate frequently in autumn, and maintain water depth above 1.5 m in winter. 

    5. Focus on timely and early induced spawning: determination of the induced spawning date: after the weather turns warm, when the minimum morning water temperature remains above 18°C for 3 consecutive days and there is no strong cold air invasion. Characteristics of mature broodstock: female fish have a swollen abdomen, the sides of the genital pore are plump, soft and elastic, the genital pore is loose; in grass carp, the scales on the abdomen are loosely arranged, the ventral midline is concave, and the ovary droops as if moving, giving a good induced spawning effect. Male fish that can release milky white semen which disperses immediately in water can all be used. Generally, female fish are injected with 1000 international units of chorionic gonadotropin per kg of body weight, or LRH-A 40-50 micrograms; male fish receive half. 

    6. Optimize the hatching process: hatching water must be filtered through a filter screen to prevent floating matter and wild trash fish from mixing in. Before each hatching, clean the hatching jars and hatching troughs; during hatching, provide a suitable water flow rate, frequently turn the water body, check whether eggs or fry have accumulated in the bottom corners, clean them promptly, and maintain water quality. 

    7. Comprehensive prevention and control of fish diseases: in broodstock cultivation, fish diseases should be mainly prevented; every spring and autumn, splash 0.4ppm crystalline trichlorfon over the whole pond to prevent parasites, and from April to October splash 30ppm quicklime or 1ppm bleaching powder over the whole pond once a month to prevent bacterial diseases. Once fish disease is found, actively apply the right medicine according to the symptoms and cure it as early as possible.