The technique of culturing Cage in River Cage

The Xinjiang River is the third largest river in Jiangxi Province, with rich fishery resources, good water quality and light pollution. The water transparency is 0.720 meters, and the total length of Yingtan section is 104.05 kilometers. Fanjiatan of Jinjiang River (Yingtan section) is relatively shallow. The total length of Fanjiatan is 2 kilometers, the deepest is 3.6m and the shallow is 0.5m. In 1999, we chose the depths of Fanjiatan to carry out the experiment of cage culture. The fish was put into the cage on March 22 and caught on December 20 of that year. After nearly 9 months (273 days) of breeding, a total of 22538 kg of fresh fish was harvested, with an average yield of 45.08kg / m2. 1 main techniques and measures: 1.1 cages and fish species. The cage adopts a double-layer enclosed polyethylene structure with a specification of 5 × 5 × 2 (m3) with inner and outer mesh of 3 cm and 4 cm respectively. In order to prevent the loss of bait, the outer layer of the cage is equipped with a frame, each box is connected with 4 bamboo bamboos, old gasoline cans are used as floats, iron anchors and bricks are used as sinkers, the cages are arranged in one shape and two wings, row spacing is 6 meters, box spacing is 1.5 meters, a total of 20 cages, a total of 500 square meters. The cage was launched 10 days before the fingerling was released. After some organisms were attached to the cage, the fish was put into the cage on March 22nd, with a total amount of 2807.9 kg, a total of 50529 fish, an average weight of 55.57g / tail, and an average stocking capacity of 101.0 fish / square meter. When the fish enter the box, wash and disinfect the fish with 12mg/L concentration of potassium permanganate or 3% salt water. 1.2 Feed and feeding. Using the formula of Beijing Agricultural University, the pellet produced by Yingtan Liangmao Feed Company, crude protein 27%-30%, crude fiber ≤ 12%, calcium 0.5%-1.3%, phosphorus ≥ 0.06%, sodium chloride 0.2%-1%, moisture ≤ 11%. Sprinkle with a small iron spoon, first domesticate for five days, so that the mackerel forms a conditioned reflex, and as soon as they hear the sound of knocking on the boat, they scramble to swim to the surface of the cage for food. Feeding persists in regular and quantitative feeding, 2 to 3 times a day, three times a day from July to September, generally at 7: 8 a.m., 11: 12 a.m. and 4: 5 p.m., feeding adheres to the principle of from less to more and faster to less. when only a small number of fish are slowly feeding on the surface of the box, the feeding is stopped, accounting for about 3% of the body weight and changing the feeding amount every 20 days. 1.3 manage 1.3.1 prevention and control of fish diseases. Throughout the breeding process, we always adhere to the principle of "giving priority to prevention, prevention is more important than treatment", and diagnose and treat any abnormal situation in time. When entering the box, the fish were washed and disinfected with 12mg/L concentration of potassium permanganate or 3% salt water for 10 to 15 minutes. About a month after entering the box, pay attention to waterproof mildew, each box with 50 grams of Chengdu produced "water mildew net" water sprinkle, sprinkle twice a day for two days. Usually, stick to the medicine bag, hang 50 g / bag of "King of Water purification" and strong chlorine to prevent disease on the opposite corner of the surface of each box, and sprinkle it with 60mg/L quicklime water twice a month during the fish growing season. 1.3.2 Flood control and escape prevention. Fish culture in river cages is a key problem for flood control and escape control. Usually the water level is relatively stable, pay attention to check and strengthen the cage in flood season, and move the cage to shelter from the wind and water. Pay attention to often patrol the box, remove foreign bodies, and set up two blocks in the culture area, on the one hand, to block the sundries floating upstream, but also to prevent ferocious fish from breaking through the cage and causing fish escape. (2) the effect of culture was 2.1. After 273 days of breeding, a total of 44454 fresh fish with a total of 22538 kg were obtained, of which the largest individual was 1600 g and the smallest individual was 270g. The average individual weight was 507g, the average unit yield was 45.08kg / m2, and the survival rate was 88%. 2.2 Economic benefits. In the experiment of cage culture in Yunban river, a total of 20 boxes were released and 22538 kilograms of fish were produced, with a total output value of 360600 yuan and a total cost of 133100 yuan, including fish seed fees accounting for 37.56%, feed fees accounting for 58.68%, medicine and labor costs accounting for 3.76%, with a total profit of 227500 yuan, with an output value of 721.2 yuan per unit area and an input-output ratio of 1 ∶ 2.71. 3 experience 3.1 flood control and escape flood control: first of all, it is necessary to select a good point, which should be selected in the migratory bay and other sheltered places with a relatively low flow velocity, with a water depth of 30.6 meters. Secondly, when the flood season comes, the cage should be checked and strengthened. The safest way to avoid the flood is to list the fresh fish that can be listed before the flood, transfer the fish that can not be listed on the market to the pond and reservoir in Wei, and then move back to the river for breeding after the flood. Anti-escape: to be familiar with the hydrological conditions of the river and the distribution of ferocious fish, block and remove sundries washed down from the upstream in time, set up 1-2 traps on the outer edge of the culture area, using two-house cages and metal cages. 3.2 Prevention of disease. In the whole process of the experiment, no serious disease occurred except for one case of water mildew in late April. The survival rate is 88%. In order to reduce the incidence of fish culture in river cages, the following three hurdles should be done well: (1) the fish species should be put into the box. When the fish species enter the box, potassium permanganate or salt water and malachite green are used to disinfect the fish. (2) low temperature off. Fish soon into the box, there is an adaptation process, fish in the box, easy to be bruised and infected, at this time should be commonly used malachite green or water mildew net and other drugs to sprinkle. (3) High temperature off. In the peak season from August to September, quicklime should be often sprinkled and bag disinfection should be carried out in the cage. 3.3 Fish species and feed. Generally speaking, the size of fish species should be larger, and 618 fish / kg should be the best. Fish species should be solved nearby to avoid the decline of resistance caused by long-distance transportation and affect the survival rate, and the stocking density should be flexibly mastered according to cage specifications, fish growth characteristics, listing specifications, technical management level, investment status and so on. In order to achieve better benefits, we can adopt the method of raising two batches of commercial fish a year, that is, around the Spring Festival, we can put 6 fish / kg and 16 million 20 fish / kg into the box, and before and after the Dragon Boat Festival, some fish can be listed on the market, and then separate boxes to strengthen management. Before and after the Mid-Autumn Festival, all the fish can be put on the market. Before and after the Dragon Boat Festival and Mid-Autumn Festival, fish in the market are generally popular and the price is strong. In addition, the fish cultivated by river cages have good body color and taste, and have strong market competitiveness. In order to reduce the loss of feed, the feeding frame can be used for puffed material, and the bait table can be set up at 30cm to 50cm below the surface of the water. Feeding should be carried out according to the method of less and slower to more and faster to less.