Culture technique of sharp-nosed sea bass

Lateolabrax japonicus, commonly known as blind fish, has the advantages of strong adaptability, large food intake, rapid growth, less disease, delicious meat and high nutritional value. it is the main economic fish in Southeast Asia. Due to the fact that it takes only about 4 months to raise the fish fry from 3-5 cm to 400-500 grams on the market, and it has a wide range of adaptation, it can be cultured in both fresh and brackish water, with a high market price (36-50 yuan per kilogram at present) and a large demand. it is regarded as the main object of pond and cage culture by Southeast Asian countries, Taiwan and Hong Kong, and it is one of the valuable economic fish cultured in fresh water and brackish water. 1. Culture conditions: 1. Fish pond conditions and supporting facilities: fish bass like to live in water with fresh water quality and rich dissolved oxygen, and have certain cluster habits, so the culture pond should be close to the source of water, good water quality, convenient access and drainage, and equipped with oxygen-increasing equipment. The area had better be no more than 10 mu, the water depth is 15-2 meters, and there is less silt. At the same time, convenient transportation is required. Pond cleaning should be carried out one month before stocking. Clear the pond thoroughly (the method of clearing the pond is the same as that of conventional fish culture). Ten days before the seedling is released, the water is 70-100 cm, and a dense net is installed at the entrance to prevent other ferocious fish from entering, and 150 kg of crude salt per mu is applied to make the pond have a certain "salty bottom". This is the key to the success of pure fresh water culture of sharp snout perch. 2, cage culture: the cage is set in the reservoir and river water depth of more than 2 meters, transparency of more than 30 cm, dissolved oxygen 4 mg / L, PH value neutral or slightly alkaline, where there is micro-fresh water, the best cage area is 24 square meters / one, the fixed mesh is more than 1 cm. 2. Desalination cultivation of seedlings the desalination cultivation of seedlings is the key technology of freshwater culture of Lateolabrax japonicus, which is related to whether it can make money and whether it can be successful. In the past, the seedlings of Lateolabrax japonicus farmed in China mainly came from Thailand, and most farmers chose seedlings of 5-7 cm or more. Due to the lack of intermediate cultivation and desalination, the purchased seedlings went directly to fish ponds, so the survival rate of seedlings was very low. Some are only 10%, 20%, and some are wiped out, preferably only 40%, 50%, which directly limits the development of this fish culture in China. It is understood that the low survival rate of Lateolabrax japonicus seedlings after being planted in the pond is as follows: first, the hatching farms of Lateolabrax japonicus in Thailand are concentrated in southern Thailand, and the seedlings sent from Thailand to China are usually transported from southern Thailand to Bangkok airport on the same day. The next morning, they were repackaged with oxygen and water to board the plane to Hong Kong, and finally reached the farmers' pond via Shenzhen, which took at least 13 hours before and after. Due to the turning point of long-distance transportation for a long time, seedlings are often injured, and the survival rate of seedlings is low after going into the pond. Second, when the larvae were transported from southern Thailand to hang water near the airport on the same day, due to the high rent at the venue near the airport and the lack of water, dealers often put a large number of fish fry in very few fish ponds, so it was easy to produce fish fry "local water". Even if the fry did not die at that time, but a large number of fish fry began to die after 2-3 days in the pond. Third, the larvae imported from Thailand are released directly into pure fresh water ponds without desalination from the "saltiest" (salinity 20 ‰), desalination rate is too fast. Due to the great difference in living environment, the survival rate of fish fry is low. Because of the above reasons, the survival rate of the seedlings purchased by farmers is very low after entering the pond, and the actual cost of the survived seedlings is very high, which reduces the benefit of breeding the sea bass. For this reason, we began to domesticate, desalinate, cultivate and succeed in the middle of the seedlings of Lateolabrax japonicus in Panyu in 1998: the seedlings imported from Thailand after 15 days of incubation (salinity 15 ‰) were gradually desalinated after 20-30 days, and the domestication process was bred into seedlings of more than 3 li meters, which are pure fresh water and can all eat pulp, with a survival rate of more than 75%. At present, the seedlings provided by the seedling base for farmers are all more than 3 centimeters of 100% pure fresh water that have been desalinated for more than 20 days. Third, adult fish culture desalinated 100% pure fresh water all eat fish pulp more than 3 centimeters of snout bass after about 4 months of careful breeding, most individuals can reach 400-500 grams on the market. 1. Culture method: the sharp snout perch is specially raised in ponds and cages, and the density pond is specialized in raising 800-1000 fish per mu. In order to improve the water quality and make full use of the residual bait, 40 bighead carp with 250g per mu and 100crucian carp with 50g can be raised per mu. Before the fry goes into the pond, it is best to remove the purse seine for 7-10 days before the purse seine is removed and transferred to the pond. There are 25 cages per square meter and 30-40 cages per square meter in places with micro-running water. 2. Feed: (1) types of feed: a, animal feed such as chilled fish; B, high-energy expanded feed. (2) feeding method and feeding quantity: determine the feeding amount according to the growth, water quality, weather and feed quality of the fish: A. the fry feed just off the pond should choose mixed fish with more meat and less bones, grinder is used to grind the meat into pulp and bone, and then add a small amount of eel feed to form a mixed feed, which is fed three times a day, the feeding amount is 50% of the body weight of the fish, and then it gradually decreases to 20%. For the first 3 days of feeding, it is best to add 5 grams of dysentery and 4 grams of oxytetracycline every 50 kilograms of feed to facilitate disease prevention. B, 10 days after the fish gradually grow up, feeding to achieve "four fixed", first go to the board after feeding, feeding first slow then fast, less frequently, evenly in a certain range of water to throw the feed, so that the feed will be swallowed by the fish when it floats into the water. C. When the fry grows to about 15 cm, it can be cut and fed with chilled fish, which generally accounts for 12% of the fish's body weight, and then gradually drops to 8% of the fish's body weight. Feed the high-energy expanded feed, the feeding amount should be controlled at 8% of the fish body weight, and the feeding amount should be adjusted every 8-10 days. In short, it is necessary to keep the spoiled feed, do not cast when the fish is anoxic, cast less when it is cloudy and rainy, do not throw when the fish stop fighting for food, and invest more when the fish grow fast, until it is on the market, and the feeding cannot be interrupted. 3. Feeding management: perch culture requires fresh water quality, high dissolved oxygen content and transparency of more than 30 centimeters, so it is necessary to change water frequently, especially in all seasons, the whole culture period needs to be sterilized with quicklime for 2-3 times. while improving the water quality, keep slightly alkaline, persist in patrolling the pond sooner or later, cage culture should often check and clean the cage to prevent mesh blockage caused by hypoxia. With the growth of the fish, the cage with large mesh should be replaced, and the whole cultivation period should be carefully recorded and summarized in time. 4. Prevention and treatment of fish diseases: if the following diseases occur, the following treatments should be carried out: (1) White spots on the body surface: the fry can be immersed in a solution with a salinity of 15% Rue 20%, or immersed in 20ppm formalin solution for 1-2 hours. (2) if there are bacteria or parasitic diseases, the following measures can be taken: a, water mildew: purple potion 10ppm bath or malachite green 0.15-0.2ppm sprinkled throughout the pond. B, parasites (rotifer, ring worm, etc.) 0.8-1ppm crystal trichlorfon sprinkled all over the pond. C, enteritis: red and swollen anus, hyperemia at the base of the fin, erythema on the abdomen, 3 grams of furazolidone for every 50 kilograms of fish, or 5 grams of sulfamethidine for 3-5 days. No matter pond culture or cage culture, sharp snout bass can obtain better economic benefits. Sharp snout bass is a freshwater culture species worth popularizing. Snout bass can be fed either chilled mixed fish or high-energy expanded feed, and the feed costs of the two kinds of feed are similar. We suggest that the ponds with good water source and good water exchange conditions can be fed with chilled mixed fish and high-energy expanded feed. Fish ponds with poor water exchange conditions or places where there is no mixed fish under chilled water, it is best to choose high-energy expanded feed. Because feeding high-energy expanded feed has the advantages of easy feeding management, labor-saving, no waste, no water pollution, less fish disease and so on. In freshwater aquaculture, fish species of more than 3 centimeters that have all eaten fish pulp after desalination of 100% pure fresh water must be selected in order to ensure that the survival rate of the seedlings is high after entering the pond, ensure that commercial fish are on the market on time, maximize culture efficiency, and avoid culture risks.