In recent years, the hybrid fish farming industry in Zhongshan, Zhuhai, and surrounding areas in Guangdong has developed more and more rapidly. The demand for hybrid seedlings has been increasing year by year, which has promoted the rapid development of hybrid seedlings and seedlings industry. However, due to the lack of strict selection of broodstock in some hatchery farms and the non-standard and unscientific production, the production capacity of the seedlings is low and the quality is uneven. It is difficult to achieve large-scale production. After years of research, the author summarizes the practice of key techniques for the cultivation of large-scale seedlings in the hybridization pots of Jiantang, so as to provide technical support for the healthy development of the hybrid tip ponds.
Pond preparation
The hybrid production of large-scale hybrids of T. edulis requires not only hatching and cultivation of fish fry, but also a bait biological pond.
Fry hatching and breeding ponds. The area is appropriated from 3 mu to 5 mu, with a water depth of 1.0 to 1.3 meters. The fry is disinfected with bleach for 10 to 15 days before hatching. Dry clear pond: depth of 5 cm to 10 cm, 4 kg to 8 kg per acre Quanchiposa bleaching powder; water clear pond: water depth of 0.5 meters, 20 kg to 40 kg per acre. After 3 days to 4 days in the clear pond, the water depth is 70 cm to 80 cm, and the inlet is filtered with 80 mesh mesh.
Feed bio-pool. Each nursery is best equipped with more than two, with an area of ​​2 mu ~ 3 acres, water depth of 1.2 meters to 1.5 meters is appropriate, 20 days before the fry production, clearing disinfection with bleaching powder (used as above), clear pond after 3 days ~ 4 days into the water, the early depth of 60 cm to 70 cm, after the appropriate amount of 5 cm to 10 cm per week, the inlet with 150 mesh mesh filter. After influent, one-time application of fermented chicken manure 100 kg / mu, while the use of fermented chicken manure bags (not less than 20 bags per acre, about 30 kilograms per bag), for timely fertilizer, to cultivate a large number of rotifers.
Spawning tube production
There is a habit of spawning in the cave or under the sinking wood in Jiantang, and it is necessary to provide an oviposition tube for spawning. Production generally use white PVC pipe (tube diameter of 15 cm to 20 cm, about 40 cm long), in the end of the tube drilled a small hole, tied a small rope, flat on the bottom or hanging in the water can be.
Egg collection and hatching
When the water temperature reaches 25°C or more, the spawning cylinder can be put in the broodstock for the natural spawning and fertilization of the broodstock. Production is generally checked one by one in the early morning of the second day after the laying of the spawning cylinder, and the spawning cylinder for collecting the fertilized eggs is transferred for hatching. The fertilized eggs are evenly arranged on the inner wall of the spawning cylinder to form an oval arrangement.
The oviposition tube with the fertilized egg is moved to the hatching and incubating in the breeding pool. It is advisable to place 100 to 150 egg-laying cylinders with a fertilized egg per acre. The hatching water temperature is hatched at about 28 to 30° C. for about 36 hours. After about 48 hours, the yolk sac disappears, and swims are started.
Fry opening and feeding management
Three days after larvae hatch, if the number of rotifers in the seedling pool is not enough, it is best to collect appropriate amount of rotifers from the bait culturing tanks for feeding. Afterwards, depending on the number of rotifers in the seedling pool, timely addition of the rotifers ensures that the organisms are adequate. During the middle and later stages of fry rearing (generally after 20 days), fish fry, leeches, or live feed fish (such as carp flowers) can be changed when the fry grows to 1.2 cm or more. For chilled fish paste, the daily dose is 12% to 18% of the fish's body weight; on water fleas, the amount of 20,000 fish per day is between 2 kg and 3 kg; Fish 100,000 to 150,000.
Water quality management
During the early fry cultivation, fresh water is added every 5 days to 7 days. During the middle and later stages of fry cultivation, the fry grows to 1.2 cm or more. After habitually sitting in the bottom of the pond, water can be changed by about 10 cm every 7 days to 10 days, after which lactic acid bacteria are applied. Good microorganisms. At the same time pay attention to open the aerator, keep the dissolved oxygen above 4 m/l.
Harvesting of fry
After the fry body length reaches 3 cm, it can be collected and transferred to the fingerling cultivation stage. The catching rate of the hybrid tip pond is higher, and the whole pool can be used for catching or placing cages for drainage.
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