For crab breeding to obtain good economic benefits, crab species, water quality, and management are indispensable factors, and quality crab species is the basis for success. How to cultivate high-quality, robust crab species is an important issue before us. In recent years, the author has conducted research on the cultivation of first-instar crabs and obtained some healthy breeding techniques. The technical points are summarized as follows:
1 Preparation for cultivating the estuary: cultivating the estuary of the first-instar crab, requiring convenient drainage and drainage, with an area of ​​about 1-2 mu. Rectangular, large-eyed larvae of the crabs should undergo strict trimming before entering the pond, and use drugs to carry out Completely clean the pond, kill all kinds of predators, do a good job of fence-fighting facilities, prevent the entry of predators; at the same time, cultivate a part of aquatic plants such as Vallisneria, water peanuts, etc. in the cultivation pond, and the area of ​​aquatic plants accounts for 30-40 of the total area. %. The water level in the cultivation pond is generally about 60cm.
2 Selection of bigeye larvae seedlings: The big eye larvae used to cultivate first-instar crabs must be seedlings that are robust, disease-free, and moderately dilute. This is whether large-eyed larvae can be successfully cultivated into first-instar crabs. The key lies. If the quality of the big eye larvae is poor and their physique is weak, there is a danger of annihilation. In the selection process of large-eyed larval seedlings, a strict inspection of the nursery site is generally required; the size of the pro-crab species used for reproduction should be above 150g, and the color of the bred large-eye larvae must be uniform and the size must be neat. , active ability to be strong. Such large-eye larval seedlings can produce high-quality first-instar crab species.
3 One-year-old crab breeding:
1 stocking of large-eyed larvae: stocking of large-eyed larvae at normal temperature is generally after May, the water temperature reaches about 20 °C, stocking density is generally 0.5-1kg/mu, a few days before stocking, to the breeding pond Red worms were placed in the pool and soya milk was splashed into the pool to develop water quality, providing sufficient feed for bigeye larvae.
2 Feeding of bait: After the big pond larvae seedlings are fed, the bait is fed according to the weight of 150-200% of the body weight every day. In the early stage of the cultivation, the bait should be refined and full, with the growth and development of the seed to five stages. Afterwards, the percentage of animal diets should be reduced on a case-by-case basis to increase the proportion of plant foods. Animal foods are mainly fish gizzards, eggs, etc. The vegetal foods are mainly various kinds of aquatic plants such as Hydrilla verticillata, duckweed, and water peanuts.
3 Changing the water: Salinity is one of the important factors that lead to the early maturation of crabs; the frequent replacement of water during the cultivation of one-year crab species not only improves the living environment of the crab species, but also reduces the salinity of the water bodies. So as to reduce the proportion of precocious puberty of first-instar crabs and increase the success rate of seed breeding. The water exchange volume is generally once in 10-15 days, and the amount of water exchanged is 1/3-1/2.
4 Grading: In order to control the ratio of precociousness of first-instar crabs, after the crabs are raised to five juvenile crabs, the larger ones of the crabs are removed from the juveniles and concentrated in a special pool for cultivation. It is controlled to inhibit its growth and development so as to control its precocious puberty.
5 Water quality regulation and disease prevention: During the cultivation of one-year-old crab species, quick lime disinfection shall be conducted every 30 days for the cultivated estuary, and 5 kg of lime shall be used per mu to control pathogens and kill pathogens besides regulating water quality. effect. For diseases such as black shank disease occurring in the course of cultivation, timely prevention and treatment with chlorine dioxide and other disinfectants can achieve better therapeutic effects and improve the survival rate of first-instar crab breeding.
1 Preparation for cultivating the estuary: cultivating the estuary of the first-instar crab, requiring convenient drainage and drainage, with an area of ​​about 1-2 mu. Rectangular, large-eyed larvae of the crabs should undergo strict trimming before entering the pond, and use drugs to carry out Completely clean the pond, kill all kinds of predators, do a good job of fence-fighting facilities, prevent the entry of predators; at the same time, cultivate a part of aquatic plants such as Vallisneria, water peanuts, etc. in the cultivation pond, and the area of ​​aquatic plants accounts for 30-40 of the total area. %. The water level in the cultivation pond is generally about 60cm.
2 Selection of bigeye larvae seedlings: The big eye larvae used to cultivate first-instar crabs must be seedlings that are robust, disease-free, and moderately dilute. This is whether large-eyed larvae can be successfully cultivated into first-instar crabs. The key lies. If the quality of the big eye larvae is poor and their physique is weak, there is a danger of annihilation. In the selection process of large-eyed larval seedlings, a strict inspection of the nursery site is generally required; the size of the pro-crab species used for reproduction should be above 150g, and the color of the bred large-eye larvae must be uniform and the size must be neat. , active ability to be strong. Such large-eye larval seedlings can produce high-quality first-instar crab species.
3 One-year-old crab breeding:
1 stocking of large-eyed larvae: stocking of large-eyed larvae at normal temperature is generally after May, the water temperature reaches about 20 °C, stocking density is generally 0.5-1kg/mu, a few days before stocking, to the breeding pond Red worms were placed in the pool and soya milk was splashed into the pool to develop water quality, providing sufficient feed for bigeye larvae.
2 Feeding of bait: After the big pond larvae seedlings are fed, the bait is fed according to the weight of 150-200% of the body weight every day. In the early stage of the cultivation, the bait should be refined and full, with the growth and development of the seed to five stages. Afterwards, the percentage of animal diets should be reduced on a case-by-case basis to increase the proportion of plant foods. Animal foods are mainly fish gizzards, eggs, etc. The vegetal foods are mainly various kinds of aquatic plants such as Hydrilla verticillata, duckweed, and water peanuts.
3 Changing the water: Salinity is one of the important factors that lead to the early maturation of crabs; the frequent replacement of water during the cultivation of one-year crab species not only improves the living environment of the crab species, but also reduces the salinity of the water bodies. So as to reduce the proportion of precocious puberty of first-instar crabs and increase the success rate of seed breeding. The water exchange volume is generally once in 10-15 days, and the amount of water exchanged is 1/3-1/2.
4 Grading: In order to control the ratio of precociousness of first-instar crabs, after the crabs are raised to five juvenile crabs, the larger ones of the crabs are removed from the juveniles and concentrated in a special pool for cultivation. It is controlled to inhibit its growth and development so as to control its precocious puberty.
5 Water quality regulation and disease prevention: During the cultivation of one-year-old crab species, quick lime disinfection shall be conducted every 30 days for the cultivated estuary, and 5 kg of lime shall be used per mu to control pathogens and kill pathogens besides regulating water quality. effect. For diseases such as black shank disease occurring in the course of cultivation, timely prevention and treatment with chlorine dioxide and other disinfectants can achieve better therapeutic effects and improve the survival rate of first-instar crab breeding.
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