Detailed Explanation of Key Techniques for Polyculture of Snakehead and Chinese Carps

Polyculture of Chinese Carps in Ponds Mainly Culturing Snakehead

Since bait is continuously applied in ponds mainly culturing snakehead, residual matter in the pond keeps increasing, and fish excrement also continuously increases, so the pond water becomes fertile quickly and is prone to aging. After polyculturing some Chinese carps, their mutually beneficial effects can be fully utilized, which can regulate water quality and increase fish yield.

1. Pond Conditions

Ponds for monoculture of snakehead can be either earthen ponds or cement ponds. The area can be large or small, ranging from a few sq m to 600-2000 sq m, but it is best not to exceed 2000 sq m. Pond depth is 1.5-2.0 m. The pond bottom has no silt, the soil quality is good, water retention is strong, and there are water inlet and drainage systems and anti-escape facilities. Where conditions permit, it is best to plant some aquatic plants such as water hyacinth or alligator weed around the pond, generally covering no more than 25% of the total area. During high water periods, when the pond ridge land is low-lying, a 1 m high bamboo fence or netting should also be set around the pond as an anti-escape wall to prevent snakehead from escaping when the ground is wet and slippery during the rainy season.

2. Pond Clearing

10 days before stocking fry, thoroughly clear and disinfect the pond with quicklime or bleaching powder. After an interval of 3-5 days, fill with water (the water source should meet @#@233@#@ water standards), with a water depth of 0.8-1.0 m. After the toxicity disappears, test the water and release the fish.

3. Fry Stocking

The stocking requirements for snakehead fry are the same as for pond monoculture, except that the quantity should be reduced as appropriate. The size of Chinese carps should be larger than that of snakehead. Under normal circumstances, the following model can be used as a reference: stock 100-200 silver carp and bighead carp per 667 sq m of water surface, at 0.3 kg per fish; 20-30 common carp, at 0.4 kg per fish; and 30-50 crucian carp, at 0.1 kg per fish.

4. Bait

Chinese carps do not need special fertilization or feeding and mainly rely on pond fertility and leftover snakehead bait. Snakehead is a ferocious carnivorous fish and can be directly fed small, palatable live freshwater and marine wild miscellaneous fish and shrimp, chopped larger fish, and can also be fed animal-based baits such as @#@261@#@, silkworm pupae, insects, and slaughterhouse livestock and poultry scraps. In places where bait fish and animal-based bait are difficult to obtain, artificial compound feed can also be fed. Feeding compound feed should involve domestication from an early stage, and small fish and shrimp or other live animal-based baits favored by snakehead must not be mixed in midway, to avoid snakehead competing for small fish and shrimp and other live animal-based baits and not eating the compound feed, causing waste of compound feed and reducing the effectiveness of later domestication, thereby affecting snakehead growth. The specific formula of compound feed can be flexibly determined according to local conditions. For example, fish meal (47%), various oilseed meals, peanut bran, wheat bran, corn meal, rice bran, etc. (48-51%), and bone meal (2-5%) can be used to make artificial compound feed containing 40% crude protein.

5. Daily Management

For polyculture of Chinese carps in ponds mainly culturing snakehead, no special management of the Chinese carps is needed; it is only necessary to manage the snakehead according to the daily management methods for pond monoculture.

Polyculture of Snakehead in Ponds Mainly Culturing Chinese Carps

Because common carp and crucian carp in ponds mainly culturing Chinese carps have strong self-reproduction ability, there are many common carp and crucian carp fry, and there are also many wild miscellaneous fish, which is not conducive to the growth of Chinese carps. Stocking a small number of snakehead can eat the wild miscellaneous fish and the self-reproduced fry of common carp and crucian carp. This not only avoids fry competing for oxygen and food, which is beneficial to the growth of Chinese carps, but also allows obtaining high-quality snakehead and increasing benefits. The specific measures are as follows.

1. Pond Conditions

The requirements are the same as those for Chinese carp ponds. Generally, ponds that can raise adult Chinese carps can be used to polyculture some snakehead. However, the pond bottom silt thickness must not exceed 10 cm.

2. Pond Clearing

10 days before stocking fry, thoroughly clear and disinfect the pond with quicklime or bleaching powder. After an interval of 3-5 days, fill with water (the water source should meet fish farming water standards), with a water depth of 0.8-1.0 m. After the toxicity disappears, test the water and release the fish.

3. Fry Stocking

Fry stocking involves many factors and must be comprehensively considered in light of local actual conditions to formulate a suitable stocking plan and obtain good aquaculture results. The stocking time for snakehead should be later than that for Chinese carps. Chinese carps are generally fully stocked by the end of March, and snakehead by the end of April.

When snakehead is polycultured with Chinese carps such as silver carp, bighead carp, grass carp, common carp, crucian carp, and tilapia, the size of the polycultured Chinese carps should be about 1 times larger than that of the snakehead to prevent them from being eaten by the snakehead. The polycultured snakehead should also be uniform in size to prevent them from cannibalizing each other.

Generally, 80-100 snakehead fry of 4-5 cm size are stocked per 667 sq m of water surface, or 40-50 of 6-7 cm size. They can grow to market size in the same year, and 667 sq m of water surface can increase yield by 50-100 kg, with output value increasing by 800-2000 yuan.

4. Bait

Snakehead polycultured in adult Chinese carp ponds does not need special feeding and mainly relies on natural bait in the pond. If natural bait is insufficient, some tilapia, Hemiculter leucisculus, Rhodeus, and topmouth gudgeon can be stocked in the pond to spawn and reproduce offspring to make up for the shortage of bait.

5. Feeding Management

For polyculture of snakehead in adult Chinese carp ponds, no special management is needed; it is only necessary to manage the Chinese carps according to daily management methods. However, when applying chemicals in the pond to treat Chinese carp diseases, ferrous sulfate should be used with caution, because snakehead is very sensitive to ferrous sulfate, and often after application the snakehead is poisoned to death while other fish remain safe. In addition, for ponds polyculturing snakehead, when draining the pond to harvest fish at the end of the year, all of them must be caught cleanly without omission; otherwise, it will be very harmful to the Chinese carp fry stocked the following year.