Giraffe is one of the most valuable freshwater fish endemic to China and is a warm water fish. Its survival temperature is 0 ~ 38 ° C, the optimal growth water temperature is 25 ~ 28 ° C, and can naturally overwinter in the pond. The fish is gentle and easy to catch, so it has the development prospects of monoculture, polyculture and large-scale breeding.
1. Fingerling breeding
Fingerling rearing refers to the rearing of "inch" (3.3 cm) fry for 4 to 5 months, so that they reach a length of 12 to 20 cm and a tail weight of 40 to 100 grams of large-sized fingerlings. Generally in the early to mid-May of that year, 2.5 to 3.3 cm of summer flower fry are purchased from the place of origin, and after long-distance nylon bag oxygenation and transportation, the physique is weakened, and should be placed in a cement pond of about 100 square meters for cultivation, with a stocking density of 200 fish / square meter, and the water level of the pond is 80 to 100 cm. During the breeding period, the pond water is easy to become fat and old, pay attention to about 30% of each water change. Fry rearing requires dissolved oxygen of more than 5 ppm and pH of 7 to 8.5. The pool water should maintain a certain degree of fertility. Longnose bass fry have significant photophobia, so they are often covered with shading mats at the deep end of the nursery pond. Stocking for 5 days to feed water fleas, the sixth day can be fed a small amount of water earthworms, and then gradually domesticated to feed with surimi eel feed, the ratio of the two began to 1:4, then turned to 1:2, about 20 days of artificial careful cultivation management, the fry grew to 5 cm. This is followed by the rearing of large-scale fingerlings, i.e. small fingerlings with a body length of 5 cm, which are stocked in ponds with an area of 667 to 2000 m2 to continue to be reared. The pond water depth is required to be 1.5 to 2 meters, and 1500 to 2000 small fingerlings are placed per 667 square meters, and about 15% of silver carp are reared. After careful artificial rearing management, the average weight of large-sized fingerlings of the year can reach 100 to 150 grams, and the largest individual can reach more than 200 grams.
2. Adult fish rearing
At present, the more successful adult fish rearing method is micro-flowing pond single culture, and rectangular fish ponds with an area of 667 to 2000 square meters are ideal. Adult ponds require a water depth of 1.5 to 2 meters, and separate inlet and drainage facilities are matched, and it is best to discharge the bottom water. Each pond is equipped with 1 to 1.5 kW aerator. Generally, the average daily water turnover should reach 15% to 20% of the whole pool, and the production can be injected with water for 2 to 3 hours a day, or it can be changed once a few days later.
(1) Stocking of fish species; 1000 to 1200 fingerlings per 667 square meters with a tail weight of 40 to 50 grams, or 600 to 800 first-year fish species with a tail weight of 100 to 150 grams, or 400 to 500 second-year fish species with a tail weight of 250 to 400 grams, plus 50 to 100 silver carp of 150 to 250 grams, 20 to 50 bighead carp, 20 to 30 to 30 fish of 30 grams, and 3 to 5 tails of mandarin, sea bass or snakeheads. Silver carp does not compete with the long-snout, and has the effect of improving water quality, a small amount of crucian carp can eat the remaining residual bait at the bottom of the bubble, and put a few carnivorous fish, which helps to control the wild trash fish in the pond, reduce the waste of feed and the consumption of dissolved oxygen.
(2) Adult feed: The protein content of adult fish compound feed is required to reach 40% to 42%. If you use fresh fish cubes as the mainstay, with a small amount of eel feed, although the cost is higher, but the effect is better, the ratio of the two is 2 to 3:1.
(3) Feeding management: The requirements for water quality in adult ponds are similar to those in seed ponds. Longnose is more demanding of dissolved oxygen. When the water temperature is at 26 ° C, if the dissolved oxygen in the water can be maintained at more than 5 mg / l, then its appetite is strong, the growth rate and feed effect are very high, if the dissolved oxygen is reduced to 3 mg / l, its feeding intake is significantly reduced, when it is reduced to 2.5 mg / l or less, the floating head phenomenon occurs, and then reduced to 1.5 mg / l below when the flood pond dead fish accident will occur. The pH requirement is pH 6.5 to 9, and the optimal range is 7 to 8.4.
The fish is a mild carnivorous fish, preferring to eat a variety of small fish and shrimp, land and water earthworms, insect larvae and snail meat. Through the domestication of conversion, it also loves to eat fresh fish nuggets and artificially formulated full-price pellet feed. Generally, it is fed twice a day, and the daily feeding amount is about 1.5% to 3% of the fish's body weight.
The adult fish rearing stage is mainly to prevent parasitic diseases such as enteritis and anchor crabs, so the pond is thoroughly disinfected with a dry method of 75 to 100 kg of quicklime per 667 square meters before stocking. Usually keep the water fresh, insist on changing the water every 10 days by 30%, and strengthen the prevention and control of fish diseases, feed diarrhea for 3 days every month, and feed 10 grams of fish per day. In addition, 0.3 ppm of PCR is sprinkled twice a month throughout the pool.