Fish Culture Technology of small Volume and High density Cage

First, the introduction and popularization of small cage fish culture technology, that is, small volume and high density cage fish culture technology, which was introduced into China from the United States in 1991. In the summer of 1994, Dr. Smith, an aquaculture expert from Auburn University in the United States, came to our province to hold the first small cage fish culture training course. Since then, this technology has been gradually promoted in our province. Huangshan, Anqing, Maanshan, Hefei, Bengbu, Huainan, Lu'an and other cities have a certain scale of aquaculture. According to incomplete statistics, the province's promotion and breeding reached 15000 cubic meters in 1999. Second, the characteristics and advantages of small cage fish culture the main differences between small cage fish culture and traditional cage fish culture are: first, the traditional cage generally covers an area of dozens of square meters, a depth of about 2 meters, and a volume of dozens to one or two hundred cubic meters, while small cages are usually 1-4 cubic meters. Second, the density of fish species in small cage is high, and the level of per unit yield is high. Third, fish culture in small cages depends entirely on artificial feeding of full-price pellet feed, and high-quality varieties that are marketable can be selected according to market demand. Small cage fish culture has many advantages in production: first, because of its small size, it adapts to a variety of water area settings, can be set in reservoirs, lakes and rivers, and can also be placed in ponds with larger area and deeper water. Second, because the unit yield of small cage is high, it is set in large water surface, and the combination of intensive culture of small cage and multiplication of large water surface can quickly improve the total yield and per unit yield level of large and medium-sized water area. Third, the small cage is easy to make, the production operation is simple, and the breeding technology is easy for the masses to master, which is very suitable for household management. Materials, manufacturing methods and settings for small cages. 1. Materials needed for cages. There are mainly polyethylene mesh, steel frame, Phyllostachys pubescens, iron wire, mesh wire, shading cloth, feed tube and so on. Polyethylene mesh is the main material of small cage production, the general selection of wire specifications for 3 × 3-3 × 4, mesh 2-3 cm, single layer. In addition, the bottom of the box needs to be covered with a tight mesh to prevent feed loss. The diameter of steel bar is 0.8-1 cm, and it is welded into a cuboid or cuboid frame according to the required size of the box, which can make the cage open as a whole, avoid the cage floating and maintain the maximum volume. Phyllostachys pubescens is 8-10 cm in diameter, determined according to the size of the cage, tied into a box and tied to the top of the cage. Because Phyllostachys pubescens is hollow and buoyant, it mainly acts as a float. In addition, the feed tube usually uses Phyllostachys pubescens, which is as long as the depth of the cage, but to break through the middle bamboo knots. Iron wire and mesh wire play a role in reinforcement. Shading cover can be used as a general rain-proof cloth, which is black and durable. The area is equal to the area of the cage. 2. The manufacture of net cages. First weld the steel frame, tighten and fix the mesh outside the frame to form a fully closed hexahedral cage, and then add a layer of dense mesh at the bottom of the box, which is 10 cm higher than the bottom of the box. Add a bamboo frame at the top of the box, set a feed tube in the middle of the cage, the lower mouth of the tube is 10-15 cm away from the bottom of the box, and then cover with a shading cloth. 3. The setting of small cages. It is required that the water quality is good and the area is wide, with large and medium-sized reservoirs and water areas with a certain degree of micro-flow being the most ideal. Cage culture areas should avoid waterways, floodgates and inlets where mountain torrents may rush in summer. The small cages should be arranged in the shape of "one", and the direction is perpendicular to the direction of the microflow in the water area, so as to facilitate the exchange of water bodies in the box. The spacing of each column is not less than 20 meters, and the spacing of each box should be more than 2 meters. The box and the box are connected by wire or steel rope, and the two ends are fixed on the shore or with iron anchors and large stones. Fourth, the varieties, specifications, density and release time of small cage culture 1, culture varieties. At present, the main varieties that can be cultured in small cages are carp, tilapia, spotted forktail, crucian carp, blunt snout bream, grass carp and so on. 2. Specifications. The small size of fish species is not conducive to feed production and feeding, but also affects the listing of commercial fish. Therefore, the general requirements of fish species in 50-75 g / tail, crucian carp, blunt snout bream can be smaller, but should not be less than 30 g / tail. 3. Release density. The suitable yield level of carp and tilapia in small cage culture is about 150-200 kg per cubic meter, and that of crucian carp is 80-100 kg per cubic meter. The fish should be the same size. 4. The release time of fish species. Carp, crucian carp and blunt snout bream can be released when the water temperature is stable at 12-15 ℃, while tropical species such as tilapia should be released when the water temperature is 20 ℃. It is worth noting that about 10 days before the fish is put into the box, the cage should be put into the water, so that some algae are planted on the net coat to form a biofilm, which can reduce the abrasion on the fish and avoid getting sick. The fish species are physically strong, and they should also be sterilized for 10-15 minutes with 3% Murray 4% salt water or 8-10mg/L malachite green solution to prevent the disease of fish. Feed and feed. 1. Feed. Comprehensive and reasonable nutrition is required. The protein content of tilapia feed is generally 28% Mel 32%, carp feed 30%-36%, grass carp feed 28% Mel 30%, and amino acids should be balanced. The size of the feed should be commensurate with the size of the fish, such as body weight 50-75 grams, particle size 2 mm; body weight 75-150 grams, particle size 3-4 mm; body weight more than 150 grams, particle size 4-5 mm. The feed should be stable in water and should not be dispersed for 10 minutes. 2. Feeding requirements. The fish can be fed the next day after the fish is put into the box. The amount of feed should be determined according to the fish body size, water temperature and so on. The water temperature is below 20 ℃, the body weight of the fish is between 50-500g, the daily feeding amount is 2.5% Mak 1% between21-25 ℃, the daily feed quantity is 3.5% Mel 1.5% between25-30 ℃, and the daily feed quantity is 5% Murray 2%. With the increase of fish body, the growth situation should be analyzed by sampling and the feed consumption should be adjusted in 10-15 days. Feed should be concentrated into the feed tube. When the water temperature is low, it is fed 1-2 times a day, 8-9 am and 2-3 pm. When the water temperature is high, it is fed 3-4 times a day, 8-9 am, 11-12:00, 2-3 pm, 5-6 pm. Sixth, daily management should be managed by special personnel. generally, one person can manage 20-25 small cages of 1 cubic meter, or 15-20 cages of 2-4 cubic meters. Observe the feeding and activity of fish every day, check the growth regularly, and find out the reasons in time when you stop eating, die fish and grow abnormally, and take improvement measures. It is necessary to strengthen safety awareness and earnestly do a good job in the "four precautions," that is, preventing the impact of floods, preventing nets from breaking and escaping fish, preventing theft, and preventing diseases. At ordinary times, make a good production record, and record in detail the time, quantity, weight, specification, feed dosage, weather change, variety and dosage of disinfection, disease prevention and treatment drugs, final output, specifications and other original data of each box of fish fingerling, so as to facilitate the summary of experience at the end of production and cost accounting.