Many difficulties in large-scale farming of yellow catfish, polyculture models work better

The yellow catfish is a benthic omnivorous fish, with tender flesh, rich nutrition and extremely high economic value, making it a farming species with great market potential. The yellow catfish has strong adaptability and grows slower than cyprinid fish, but grows relatively fast for the species itself; fry bred in the same year can reach marketable size within that year, and the population yield is relatively high. Because large-scale artificial farming currently faces certain difficulties, carrying out polyculture has become imperative. Polyculture of yellow catfish in fish ponds has the following advantages: first, it can feed on low-value small miscellaneous fish and shrimp in the pond, residual feed of fish, organic debris, zooplankton and so on, increasing the net yield of the fish pond. Second, the yellow catfish feeds on parasites such as anchor worms in the water body, which can reduce the occurrence of fish diseases. Third, without affecting the yield of the main farmed species, adding 5 kg to 20 kg of yellow catfish per mu can increase profits by several hundred yuan or more per mu. The polyculture techniques are introduced as follows:

Polyculture in grow-out fish ponds

Polyculture of yellow catfish in grow-out fish ponds has no strict requirements for the main fish species in the pond. Fish ponds raising the four major Chinese carps and ponds mainly raising feeding fish (such as common carp and crucian carp, tilapia, freshwater pomfret) and others can all be used for polyculture of yellow catfish. The fish pond area is 20 mu to 30 mu, water depth 2 m to 2.5 m, with sufficient water source, good water quality and convenient water intake and drainage. Generally, 40 to 50 yellow catfish are stocked per mu, at a size of 3 cm per fish to 4 cm per fish, which can increase yellow catfish yield by 5 kg to 8 kg per mu.

Polyculture in broodstock ponds

Polyculture in broodstock ponds can not only make full use of the water space of the broodstock pond and improve the utilization rate of the broodstock pond, but the yellow catfish can also feed on some small wild fish in the broodstock pond that compete with the broodstock for food and consume oxygen. After the artificial breeding of broodstock is completed, stock 40 to 60 yellow catfish per mu, at a size of 2 cm per fish to 3 cm per fish, which can increase yellow catfish yield by 6 kg to 10 kg per mu.

Polyculture in adult crab ponds

Polyculture of yellow catfish in crab ponds can make full use of the natural bait organism resources in the crab pond. Generally, the crab pond area is 30 mu to 50 mu, with an aquatic plant coverage rate of about 50%; after the crab seed is stocked, stock 30 to 50 yellow catfish per mu, at a size of 3 cm per fish to 5 cm per fish, which can increase yellow catfish yield by 5 kg to 10 kg per mu.

Polyculture in rivers and ditches

There are many low-value wild miscellaneous fish in rivers and ditches, and polyculture of yellow catfish can save artificial bait. Generally, stock 40 to 60 yellow catfish per mu, at a size of 2 cm per fish to 4 cm per fish, which can increase yellow catfish yield by 6 kg to 12 kg per mu.

Polyculture in large water bodies

Polyculture of yellow catfish in large water bodies gives a high population yield, neither affecting the yield of the main farmed species nor requiring additional bait. Generally, stock 40 to 60 yellow catfish per mu, at a size of 3 cm per fish to 4 cm per fish, which can increase yellow catfish yield by 8 kg to 15 kg per mu.

No matter which polyculture method is adopted, the following points need attention in farming management:

First, maintain a relatively high dissolved oxygen level in the water body. The yellow catfish has relatively high requirements for dissolved oxygen in pond water, so polyculture requires fresh water quality and sufficient dissolved oxygen; new water should be added in a timely manner during the growing season, and water should be changed frequently during the high-temperature season, with micro-flowing water being even better.

Second, maintain a reasonable stocking density and stocking size. According to the bait organism biomass in the water body, scientifically and reasonably determine the polyculture ratio and stocking size; generally, 30 to 60 fish per mu of water body is appropriate, with a stocking size of 3 cm per fish to 4 cm per fish. If the density is too high and the size too small, they will not reach marketable size by the end of the year.

Third, after polyculture of yellow catfish in a fish pond, it is no longer suitable to polyculture other carnivorous fish, and yellow catfish should not be polycultured in ponds for farming freshwater prawns or freshwater crayfish.

Fourth, during the farming process, if the yellow catfish are found to be too small, it indicates that the natural bait organism biomass in the fish pond is insufficient; small miscellaneous fish and shrimp, summer fry of domestic fish may be appropriately added, or artificially formulated special yellow catfish bait may be fed. When feeding artificial bait, the main farmed species should be fed first (put into the shallow water area), and then the yellow catfish (put into the deep water area). The yellow catfish has the living habit of hiding by day and coming out at night, so bait should mainly be fed at night.

Fifth, when yellow catfish are polycultured in crab ponds, because the river crab and the yellow catfish occupy the same water layer position ecologically, competition for the ecological niche between the two is easily caused. Therefore, sufficient natural bait organisms must be maintained in the crab pond, otherwise the rearing effect of the yellow catfish will be affected. In advance, 300 kg to 400 kg of spiral shells per mu can be put into the crab pond, as well as some egg-bearing crucian carp and egg-bearing freshwater shrimp, allowing them to reproduce naturally for the river crab and yellow catfish to feed on freely.