The main culture of mandarin fish in the pond needs to take good care of the five levels.

In recent years, mandarin fish artificial culture in China has developed rapidly, and the author has been engaged in mandarin fish pond culture for many years since 2003, and achieved certain results. Now the production experience in the past few years is summarized as follows, in order to provide dinner for colleagues in aquatic products.

First, strictly control the conditions of pond culture

Mandarin fish ponds require that the sediment is flat and the silt is less than 15cm. The effect of culturing mandarin fish in sand bottom ponds and newly dug ponds is better. The area of the pond is too large, which is disadvantageous to the predation of mandarin fish, the area of the pond is too small, and the water quality of the pond is not easy to be controlled, so it is easy to cause hypoxia and flooding pond. Because mandarin fish like fresh and high dissolved oxygen water quality, the main culture pond should have sufficient water source, convenient entry and drainage, and the normal water storage depth should not be less than 2m.

Second, strictly control the stocking of fish.

The stocking density of fish species should be determined according to water quality, abundance and shortage of bait fish, climate and management level. Generally in the Yangtze River basin, at the beginning of June every year, 800 million mandarin fry of 4~5cm can be released per mu; or through intensive cultivation of 20 to 25 days, the mandarin fry of 4~5cm can be raised to 10cm or so, and then put into ponds, which can greatly improve the survival rate of culture.

Third, strictly put bait fish into the customs.

Mandarin fish feed on fish and shrimp all their lives. The species, size and quantity of bait fish have a great influence on the growth of mandarin fish.

According to the author's observation for many years, different kinds of bait fish and mandarin fish of the same specification most like to eat wheat ear fish and mud carp, followed by carp, grass carp, crucian carp, bighead carp, silver carp and so on. Generally speaking, the size of the feed fish should be the length of the mandarin fish. The bait fish is too small, which is not conducive to the growth of the mandarin fish. If the bait fish is too large, the mandarin fish may trap the mandarin fish after starvation, or injure the digestive tract of the mandarin fish and cause infection.

In order to ensure the supply of food fish, the area of the main culture pond and the feed pond of mandarin fish should be matched at 1:3, in which the matching method of pre-feeding fish is to make use of the free time before stocking mandarin fish to cultivate early-stage bait fish in the pond, that is, 40 to 500000 bait fish per mu should be put in 15 to 20 days before mandarin fish stocking, which can be cultivated by conventional methods. The matching methods of bait fish in the middle and later stage of culture are as follows: multi-pond, high-density feeding, one-time feeding, separate fishing, and gradually sparse culture methods to ensure the synchronous growth of bait fish and mandarin fish. Usually this method can raise 30 ~ 50 000 water spray per mu of water surface. Bait fish are cultivated by the combination of fertilization and commercial feed.

In order to make the best use of the bait, the feeding of bait fish should be arranged scientifically, and the feeding amount should be moderate, once in the early 5-7 days and once in 3-5 days in the high temperature season from July to September. The daily food intake of mandarin fish is related to the season. The feeding amount from June to July is 15% of the body weight of mandarin fish, 20% of the body weight of mandarin fish, 10% of the body weight of mandarin fish from August to September, 15% of the body weight of the fish from October to November, and 5% of the body weight of the mandarin fish. If the bait fish is fed too much each time, it will increase the total oxygen consumption of the culture water and cause hypoxia; each time the bait fish is fed too little, the mandarin fish will consume too much physical energy, which is disadvantageous to the growth.

IV. Strict control of water quality

Mandarin fish have higher requirements for aquaculture water, so they should inject water frequently, change water frequently and increase oxygen frequently. If the mandarin fish has been cultivated in the main culture pond, part of the old water should be replaced before the mandarin fish fry go into the pond, so as to improve the current situation that the water quality of the fodder fish is too fertile.

Generally speaking, the water level of mandarin fish in the early stage of main culture is shallow, about 70~80cm, which is beneficial to the predation of mandarin fish and can improve the survival rate of mandarin fish culture. Water injection begins after 1 week of culture, and then every 5-7 days, every time 20~30cm. In the high temperature season from July to September, the water is flushed every 3 to 5 days, and the water is changed about every 15 days, which is about 20% and 30% of the pool water. In order to increase the amount of dissolved oxygen in the water body, reduce the bait coefficient, and speed up the material circulation in the water environment, the aerator should be turned on at the right time, usually at noon on a sunny day, in the early morning on a cloudy day, and in the middle of the night, so as to make it hot for a long time, cool for a short time, and a long start-up time in the middle of the night and a short start-up time at noon. In addition, mandarin fish are sensitive to acidic water, about every 20 days. Quicklime 15kg should be sprinkled on each mu of water.

5. Strict control of diseases

It is necessary to adhere to the principle of "giving priority to prevention and combining prevention with prevention" to eliminate the hidden dangers of disease to the maximum extent. To this end, one is to do a good job in pond disinfection, where there are conditions to expose ponds, or refer to conventional methods per mu of water surface and sprinkle the whole pond with quicklime. Second, the fish species are disinfected in the pond. Usually strong fish species are washed with 3%-5% salt water before going into the pond. Third, bait fish disinfection, in order to put an end to the disease from the mouth and the source of the disease, all bait fish should be disinfected. During the season with high incidence of bacterial venereal diseases, bait fish are usually washed with 10ppm bleach solution for 10 minutes; in the season with high incidence of parasitic diseases, bait fish wash 3~5min with 3% and 5% salt water, or 10min with 8ppmCuSO4 solution. Fourth, tools disinfection, to wash frequently, sun fishing equipment, if necessary, but also with CuSO4 or bleach solution immersion disinfection, in order to kill harmful bacteria. Fifth, ecological prevention and control, it is necessary to regularly sprinkle biological fertilizer to keep the water environment in the best condition. Sixth, regular prevention, alternating use of CuSO4, FeSO4 mixture (O.7ppm), bleach (1.2ppm), and the third generation of Xianan (O.1ppm), sprinkled once every 15 to 20 days to kill the pathogenic bacteria in the water and cut off the transmission of bacteria. Seventh, choose the right medicine and prescribe the right medicine to the case. Bacterial rotten Gill disease can be sprinkled with 85% trichloroisocyanuric acid O.4~0.5ppm whole pool, rotifer and oblique tube disease can be sprinkled with CuSO4 and FeSO4 mixture 0.7ppm, Chinese flea disease can be sprinkled with trichlorfon powder 2.5% and FeSO4 mixture 1.4ppm whole pool, bleeding disease can be sprinkled with third generation shrimp an 0.1ppm whole pool.