How to do cage culture of mandarin fish? Detailed explanation of key technical points

Mandarin fish, also known as the Chinese perch, is one of the valuable freshwater fish species. Cage culture of mandarin fish has the advantages of occupying less water surface, low investment, short culture cycle, high yield and good economic returns. The cage culture techniques for mandarin fish are introduced below.

Water area selection: The water area where cages are set up requires an open water surface, far from navigation channels, stable water level, slow water flow, clear and pollution-free water quality, convenient transportation, abundant natural feed and no predators.

Cage setup: The cage size is generally 5×5×2.5 m, with a submerged depth of 1.8-2 m, and the cage bottom 20-30 cm above the water bottom. The four corners of the cage are fixed with 4 bamboo poles, and the four bottom corners are anchored with stones to prevent the cage from being washed away by water currents and wind waves.

Fry stocking: For cage culture of mandarin fish, the species should preferably be the big-eyed mandarin fish or the topmouth culter. Before stocking the fry, soak them in 3-5% saline solution for 5-10 minutes, or in 1% povidone-iodine for 10-15 minutes. The stocking time is generally in mid-to-late May, with 30-40 mandarin fish fry of 4-6 cm size stocked per square meter.

Feed feeding: For cage culture of mandarin fish, forage fish such as mud carp, silver carp, bighead carp and crucian carp can be used. Among them, mud carp gives the best feeding results, with a low feed conversion ratio, and the mandarin fish grow quickly after feeding on them. The forage fish should be robust, uniform in size, free of disease and injury, with a body length 1/3-1/2 of the mandarin fish's body length. If the sizes are uneven, a fish sieve can be used to remove forage fish that are too large or too small. The forage fish are disinfected and sterilized before being put into the cage. Because cage culture has a high stocking density, too many forage fish should not be fed each time. In the early stocking period, feed once every 2-3 days; as the mandarin fish grow, change to feeding once a day. The feeding time can be chosen in the evening, when mandarin fish are most active in feeding. The daily feeding amount is 5-10% of the body weight of the mandarin fish in the cage.

Daily management. Inspect the cage once each in the morning, at noon and in the evening. When forage fish in the cage are insufficient, replenish them in time; forage fish that are too large for the mandarin fish to eat should be removed promptly. Regularly clean the attachments on the cage body to facilitate water exchange inside and outside the cage, maintain a relatively high dissolved oxygen level in the cage water, and promote the feeding and growth of mandarin fish. If the cage is found to be damaged, sew and repair it in time to prevent fish from escaping.

Fish disease prevention and control. Common diseases in cage culture of mandarin fish include bacterial gill rot, red skin disease and trichodiniasis. In seasons when fish diseases are prone to occur, hang baskets and bags alternately at the four corners of the cage with bleaching powder, a copper sulfate and ferrous sulfate mixture, and special deworming agents for mandarin fish for disinfection. Once fish disease is found, correctly diagnose it, apply the right medicine and treat it early.

Timely harvesting. After 3-4 months of culture, some mandarin fish reach market size and should be caught and sold in time to reduce the density in the cage, allowing small-sized mandarin fish to continue growing and increasing the culture yield.