Technical Measures for Increasing Yield and Efficiency in Polyculture of Mandarin Fish

Monoculture of mandarin fish requires an adequate supply of matching forage fish, has relatively high technical requirements, and presents certain difficulties for large-scale farming. Mandarin fish can be polycultured in other aquaculture water bodies.

I. Polyculture Methods

1. Polyculture in adult fish ponds. For ponds raising predatory fish, abundant water sources, good water quality, and convenient water intake and drainage are required, with an area of 5-10 mu and a water depth of 2-2.5 m. Generally, 50-80 one-year-old mandarin fish fingerlings or early-bred mandarin fish summer fry are stocked per mu.

2. Polyculture in new fish ponds. After the artificial breeding of broodstock is completed, 50-100 mandarin fish summer fry with a body length of 5-8 cm are stocked per mu, which can increase commercial mandarin fish by about 15 kg.

3. Polyculture in adult crab ponds. After crab seed stocking, 4-5 two-winter-old crucian carp are stocked per mu to allow them to naturally reproduce fry as first feed for mandarin fish. 15-20 mandarin fish summer fry are polycultured per mu, which can increase commercial mandarin fish by 5-8 kg per mu.

4. Polyculture in large water bodies. Generally, 25-30 mandarin fish fingerlings or summer fry are stocked per mu, which neither affects the yield of conventional fish species nor requires additional feeding of forage.

5. Polyculture in small ditches. Small ditches contain many wild trash fish, so mandarin fish can be polycultured there. Generally, about 30 large-size mandarin fish fingerlings of over 50 g are stocked per mu.

II. Precautions

1. Maintain a relatively high dissolved oxygen level. Mandarin fish have relatively high requirements for dissolved oxygen in water. The water surface for polyculturing mandarin fish should have fresh water quality and sufficient dissolved oxygen. It is best to plant a certain amount of aquatic plants. During the growing season, new water should be added frequently, and during the high-temperature season, water should be changed frequently. If micro-flowing water can be maintained, so much the better.

2. Ensure adequate forage. Mandarin fish are ferocious fish and extremely voracious. When forage is insufficient or not palatable, they may cannibalize one another. Therefore, before stocking mandarin fish fry and fingerlings, the number of forage fish in the polyculture pond should be investigated. If the number of forage fish is relatively small, trash fish or summer fry of domestic fish should first be introduced into the pond. The length of forage fish is required to be between 2/5-3/5 of the length of the mandarin fish.

3. Use drugs with caution. Because mandarin fish are extremely sensitive to some commonly used drugs, such as trichlorfon, malachite green, formylarsonic acid, copper chloride, mercurous nitrate, etc., their use should be prohibited in mandarin fish farming. Disease prevention and treatment in water surfaces where mandarin fish are polycultured can adopt: thorough pond clearing and disinfection before fry and fingerling stocking to create a good living environment; regular splashing of low-concentration quicklime solution; ecological prevention and treatment measures such as splashing photosynthetic bacteria, Xifeili, and other biological preparations.