Knowledge Title: Breeding of fish seedlings

Other Title: rearing offish fry and fingerling

Knowledge Content:

    The process of breeding fish fry into edible species or releasing fish species. Fish fry body is weak, poor strain ability to the environment, narrow range of food, active feeding capacity is not strong, easy to die and attackby, so must be in the artificial control of the smaller water body to give fine feeding management, cultivate a certain specification of strong species. Seedling cultivation is an important part of the fish farming process.

    The breeding of farmed fish seedlings can be divided into two methods: hydrostatic water cultivation and water culture cultivation.

    Hydrostatic cultivation is generally fertilized in a pool to reproduce the natural food of fish such as rota, supplemented by artificial feed. This is the traditional method of cultivating freshwater fish seedlings. It is also such that seedlings are cultivated using larger water bodies such as Lake, Kuwan and so on. The whole process is divided into two stages: the first stage is the fish fry cultivation stage, is the full length of 6 to 9 mm of fish fry, after 15 to 30 days of cultivation, the formation of a total length of about 3 cm “summer flower” species. The second stage is the breeding stage of the species, is the “summer flower” pond breeding, after 3 to 5 months of cultivation, to develop a full length of 10 to 17 cm, weight 10 to 50 grams or more of the year's species. Herring, grass fish of the year fish species to become a 2-year-old species, can be raised with a special pool, but also in the pool of cultured edible fish.

    The main technical links of hydrostatic cultivation: (1) fish fry pond and fish seed pond preparation. The size of the two are 2 mu and 5 mu, respectively, the water depth is about 1 meter and 2 meters, respectively. The bottom of the pool is flat, there is no large amount of silt, weeds, close to the water source, note, drainage is convenient, the water is not polluted, the oxygen content is high, the light is sufficient. Before seedling sin sits into the pond, lime or tea meal, bleach, etc. must be cast in the pool to eliminate pests and diseases and kill wild fish. Raw lime can also make the water slightly alkaline, increase the concentration of calcium ions in the water, exchange release of phosphoric acid, ammonium, potassium plasma adsorbed by the sludge, improve the fertility of water, improve water quality, can be stocked after the disappearance of the drug. (2) Seedling seculture. Fish fry stocking density is generally about 100,000 tails per acre, fish species density according to the required specifications, generally per acre stocking of 10,000 tails, that year can grow to more than 13 cm; Cultivate fish fry using single-breeding. Cultivating fish species is often mixed (generally grass fish or herring-based, with the upper-level fish such as slugs, slugs, slugs, slugs and other middle and lower-level fish mixed breeding), can make full use of the bait in the water, but also control the fertility of water. (3) Fertilize and feed the feeding material. Fish fry under the pond before fertilization and culture of plankton as bait, and then to the pool fertilization (green fertilizer, manure or inorganic fertilizer), according to the fertility of water, daily application 1 to 2 times or several days, each acre of water surface at a time to apply tens to hundreds of kilograms of organic fertilizer. In addition to fertilization, the appropriate amount of feed commodity feed. Soy milk acts as both fertilizer and bait, and is used in many parts of China to raise fish fry. Can also use water peanuts, water lily, water gourd and other aquatic plants into grass milk instead of soy milk. Fish species are bred to feed commodity feed, except for the application of appropriate amounts of fertilizer to reproduce natural bait. The cultivation of grass fish, clumps and mussels and other species should also be fed to the young leaves of Wuping, young water grass or land-based undergraduate plants, feeding 1 to 3 times a day. (4) Improve water quality. During the breeding of seedlings, new water should be filled in time to increase the amount of water and dissolved oxygen in the water and improve water quality, promote the reproduction of bait organisms, and accelerate the growth of fish bodies. (5) Fish body “exercise”. “Summer flower” and the year before the fish out of the pond, must be fish body “exercise”, that is, the fish caught in the net into the box intensive time, once a day or the next day, a total of 2 to 3 times (see photo). After “exercise” of the fish body is strong, can withstand the pond, transport and other operations. Fish discharge a large amount of mucus and feces during “exercise” and prevent deterioration of water quality during transport.

Water cultivation refers to the high-density cultivation of seedlings in small water bodies such as cement ponds, and only baiting and not fertilizing, which is a late-developed cultivation method. Generally feeding artificially cultured live bait or artificial preparation of the appropriate and nutritional value of the more complete bait. This way can save land and increase the density of seedling cultivation. Common in the cultivation of rainbow trout, eels and many marineculturefish: (1) cold-water fish (rainbow trout, etc.). The water quality is required to be fresh and the dissolved oxygen level is high (6.4 mg or more per liter of water), so the flowing water state should be maintained. The first hatched fish fry in the feeding tank or small cement pond temporary breeding, per square meter of 10,000 tails, 50,000 fish fry should maintain 60 liters per minute of flow water. When the fish fry began to swim in the water active feeding, should be timely feeding water fleas, cooked egg yolks (turned into slurry), animal liver and raw fish meat (made into paste), 6 to 8 times a day. Rearing for 1 to 2 months, weight up to 0.5 to 1 gram after moving into the fish pond culture. The area of the fish pond is several square meters to 20 to 70 square meters, the water depth is 60 cm, and the water gate is set up, the bottom of the pool has a certain slope, which is convenient for sewage. The density per square meter from 500 to 1000 tails, gradually reduced to 200 to 300 tails. Grow saves as the fish increases the flow of water. Feed 4 to 6 times a day, after 6 months or so to develop 20 grams of fish species. (2) Marine culturefish seed cultivation. It is usually divided into two stages. Take The Japanese cultivation of real seedlings as an example, the first stage in the static water or slow flow of cement pool, the pool area of 10 to 200 square meters, the depth of the pool 1 to 1.5 meters, the density of fish fry per square meter 1 to 50,000 tails. On the 10th day, slow flow began, and the amount of water exchanged in the pool increased from one-third of the daily amount of water to two times the amount of water in the replacement pool. The first half of the month feeding the rote worm, after the auxiliary feeding of foot and fish, etc. , after 30 to 40 days long to 1 to 1.6 cm, that is, into the late thinning, density from 5000 tails per square meter gradually reduced to 300 tails, and after 30 to 40 days to develop 3 to 5 cm of fish species.

    The cultivation of seedlings with closed fish farming devices is a relatively advanced way to cultivate seedlings in current running water, which can not only greatly save water, but also make many breeding conditions artificially controlled, and are found in the cultivation of eel seedlings. Cement pool area of 10 to 30 square meters, water depth of 1 meter. Water through the biofiltration pool filter, to keep the water clean, recycling water flow per hour to replace the pool water 1.5 to 2 times. A constant water temperature (around 25 degrees C) suitable for the growth of eel seedlings is caused by artificial temperature increase. The stocking per square meter, 0.2 to 1 gram of heavy eel seedlings for 1.5 kg, 1 to 5 grams of small eel species when 3 kg, 5 to 20 grams of eel species for 6 to 9 kg. Start a few days to feed silk, clam meat, etc. , and later feed with the bait.

    In addition, seedlings can be cultivated using lakes, kubay and rice fields. Plant temperature drainage or geothermal water can also be used to cultivate warm or tropical fish seedlings.