Breeding conditions should be suitable.

The cage culture of grass carp should choose places with leeward and sunny, open water surface, stable water level, fresh water quality, pollution-free water source and convenient transportation. It is required that the water body is rich in dissolved oxygen, the pH value is 7.0 ~ 8.5, the water depth is 4 ~ 5 meters, the water transparency is more than 50 cm, and the dissolved oxygen is about 5 mg/L. Moreover, the water conservancy facilities in the culture area are complete, which can be drained for irrigation and is not easily affected by floods.

Cage settings should be reasonable.

The cage should be made of polyethylene, with a double-layer structure, with a knotless cage (closed) inside and a nodular cage (open) outside. The upper cover net is a single layer, with an inner net of 3 cm ~ 3.5 cm and an outer net of 4 cm. The size of the cage can be 5 m× 5 m× 2.5 m, and the frame of each cage is supported by four bamboo strips with a length of 8 m.. The sinker is made of feldspar and tied to the four net corners below the cage, so that the cage can be fully unfolded and shaped in the water. The cage is fixed with a cable, which is a thick polyethylene rope with a diameter of 4 cm. The cable passed through the water, straightened and tied to the fixed pile on the shore. The distance between the two cables is 8 meters. After the cage is fixed with cables, the top of the cage is 20 cm ~ 30 cm above the water surface. The net cage should be installed and launched 10 day after the fish enters the box, so that algae can adhere to the net coat to make the net smooth, and the net coat should also be prevented from scratching the fish body after the fish enters the box, because the fish is generally uncomfortable after entering the box and is easy to collide and scratch. Cages can be placed in a box or in a group of boxes. The spacing between single boxes is more than 25m. When set in groups, every 5 ~ 10 boxes are grouped in series, single row or double row. The group box spacing is 4m, and the group spacing is about 100m. The arrangement direction of cages should be perpendicular to the direction of water flow. In order to prevent debris from damaging the cage, fences should be set up outside the aquaculture waters.

Fish farming should be scientific.

Four aspects should be grasped in stocking fish species: First, the fish species should be excellent, healthy, neat in specifications, complete in scales and wings, and free from diseases and injuries. The fish in the box should be healthy, avoid trauma and prevent the net from scraping the fish's mucus, because the fish's mucus can bond and remove attached microorganisms and debris, which is the first barrier for fish to resist diseases. Therefore, when choosing fish, it is advisable to be smooth and sticky, not rough. When fishing, you should follow the direction of the fish swimming, and don't fish head-on to avoid injury. Second, the specifications should be large. When releasing fish, large fish species of more than 20 cm should be released, which has strong disease resistance, high survival rate and short breeding cycle and can be listed at the end of the year. Third, the density is appropriate. Generally, the size of grass carp in cages is 300g/tail to 500g/tail, and the stocking amount is about 20g/m2 to 25g/m2. Some silver carp and bighead carp with 200g/tail to 300g/tail and100g/tail can be caged. The fourth is to pay attention to methods. Fish should be bathed and disinfected before entering the box to kill parasites on the body surface and reduce the spread probability of pathogens. Generally, it can be soaked in 3% ~ 5% saline or 20ppm potassium permanganate for 15 minutes. The stocking time is usually in late autumn or early winter, and the water temperature is about 65438 05℃. At this time, grass carp can still eat after entering the box, and there is a recovery period. After spring, they can eat early, which increases the growth time of fish and lays the foundation for high yield and efficiency.

Feed should be carefully fed.

In cage culture of grass carp, it is generally not appropriate to feed grass in large quantities, because it is difficult to promote the growth of grass because of insufficient nutrition. Full-price pellet feed should be fed to improve feed utilization rate and reduce the pollution of residual bait to water quality. Grass carp can be fed 2 ~ 3 days after being put into the box, and domesticated before feeding. According to the rhythm of "slow-fast-slow" and the feeding amount of "less-more-less", domesticate for 10.5 hours every day, and after continuous domestication for10, when most fish can float to grab food, the feeding amount is 3% ~ 5% of the total weight of the fish, 3 ~ 4 times a day, each time. The feeding amount should be adjusted reasonably according to the changes of water temperature, weather, fish intake and activity. Feeding methods should pay attention to the "four fixed" principle. Throw a small handful of bait, and then sprinkle a second one after eating. When the fish are not in a hurry to eat, you can slowly throw in a small amount, so that the weak fish can also eat the feed and ensure their balanced growth. Grass carp grows fastest when the water temperature is 25℃ ~ 34℃, so the feeding amount should be increased, and it should be reduced or stopped in rainy, sultry and thunderstorm days. Green feed can be fed once a night, disinfected with 1% bleaching powder and put into a cage, and the feeding amount is subject to leaving no grass the next day.

Daily management should be strengthened.

The daily management of grass carp cage culture is very important. Mainly do a good job in the following aspects: (1) Insist on box inspection. It is necessary to patrol the box every day, regularly check the growth of fish, reasonably adjust the feeding, carefully observe and analyze the fish situation, handle problems in time when they are found, and keep a log of cage culture to record the daily water temperature, food intake, feeding amount, dead fish and diseases. (2) Brush the box frequently. Wash the cage every 18 to 15 days to remove the residual bait dirt and attached algae, so that the water body can be fully exchanged. (3) Check the boxes regularly. Check the cage regularly, and repair it in time if it is damaged, so as to avoid fish escaping from the net or fierce fish entering the cage. During the flood season, it is also necessary to check the rope strength, whether the cable is firm and whether the mesh is deformed in time. (4) Switch the box frequently. With the fluctuation of reservoir water level, it is necessary to adjust the cage to a position with suitable water depth and quality.

Attention should be paid to the prevention and treatment of fish diseases

First of all, we must adhere to healthy farming and operate according to the rules to prevent problems before they happen. Secondly, prevention and artificial immunization should be done well. Generally, the plasma inactivated vaccine of grass carp's "three major bacterial diseases" and grass carp hemorrhagic disease tissue is injected before entering the box, ranging from 0.2 ml to 0.5 ml, and fish over 8 cm can be injected, mainly at the base of dorsal fin and ventral fin. At the same time, the fish should be disinfected with salt water before entering the box, and disinfected regularly to prevent diseases. Feed bait every 10 day for 3 ~ 5 days continuously to prevent fish from parasitism. Every 10 ~ 15 days, sprinkle 150g ~ 200g quicklime on each cage while it is hot to purify the water quality. Use pesticides and fungicides to fill the box every month. Bags can be hung around the cage in high temperature season, and the medicine can be a mixture of bromochlorohydantoin, copper sulfate and ferrous sulfate. In addition, pay attention to the green feed must be disinfected before feeding. Adhere to feeding high-quality feed, and do not feed spoiled or expired feed. Grass carp cultured in cages are generally prone to water mold, erythroderma, gill rot, enteritis, hemorrhagic disease and so on. When a disease occurs, professional and technical personnel should be asked to make a correct diagnosis and prescribe the right medicine, and it is not allowed to treat it indiscriminately, resulting in man-made losses.