Three Major Technical Measures for Safe Overwintering in Snakehead Fish Farming

Although the value of snakehead fish is now gradually being recognized by more people, and more and more people are farming snakehead fish, anyone who has raised snakehead fish knows that snakehead fish are suited to warm environments. Once winter arrives and the temperature turns cold, the management and feeding of snakehead fish becomes much more difficult.

Three Major Measures for Safe Overwintering in Snakehead Fish Farming

Snakehead fish are bottom-dwelling fish. Their survival temperature range is 1°C to 36°C, the suitable water temperature for growth is 13°C to 30°C, and the optimum growth temperature is 25°C to 28°C. When the water temperature drops below 6°C in autumn, snakehead fish move slowly and often hide in deep water; when the water temperature is too low in winter, they lie dormant in the mud at the bottom. During the overwintering period, farmers assume that snakehead fish eat little or no feed and relax their management, which can easily lead to mass mortality of snakehead fish (especially severe for small-sized fingerlings). Therefore, to ensure the safe overwintering of fingerlings, the following work must be done well:

1. Scientific feeding

1. Feeding should be relatively rationalized: it is necessary both to ensure that the snakehead fish eat their fill and to take into account that the farming environment is not polluted and that costs are saved, so scientific feeding must be carried out. When the water temperature is below 15°C, feed less; when below 8°C, do not feed. On warm, sunny and windless days, feed more; during strong winds, heavy rain, or low air pressure, do not feed. When water quality is good, feed more; when water quality deteriorates, do not feed.

2. After entering autumn and winter, the water temperature begins to drop, which is highly stressful for snakehead fish. Anti-stress additives such as VC and VE should be added supplementally to the snakehead feed. VC and VE have effects such as enhancing disease resistance and immunity, promoting growth, and increasing the survival rate. Before feeding, dissolve VC at 1.5 g/kg of feed and VE at 0.1 g/kg of feed into clean water (using 0.2 to 0.4 kg of water per kg of feed), stir evenly, and let the feed absorb it before feeding. Commercial compound vitamin preparations can also be added to the feed, with usage and dosage according to the product instructions.

3. After the beginning of spring the following year, the air temperature gradually rises and snakehead fish begin to feed. However, because in early spring the digestive and absorptive functions of snakehead fish are in a recovery period after atrophy, their function is not strong enough; repeated weather changes, fluctuating temperatures, frequent cold air activity, unstable water temperature, and pond water quality and other factors all affect their feed intake. The feeding amount should be determined according to water temperature, the size of the snakehead fish, pond water quality, weather conditions, feed type and other conditions. Never overfeed.

2. Maintaining good water quality

1. During the overwintering period, a stable water depth of more than 1.5 m beneath the ice must be ensured. Ponds with severe water leakage are not suitable as overwintering ponds.

2. Maintain the fertility of the pond water. The water in overwintering ponds should maintain appropriate fertility; the photosynthesis of phytoplankton can be used to keep relatively abundant dissolved oxygen in the water. If the water color changes, becomes turbid, turns black, or has a fishy odor, it indicates that the water quality has deteriorated and new water needs to be replaced in time. After snow falls during the overwintering period, the snow on the ice surface should be cleared in time so that the ice surface transmits light well, ensuring that the photosynthesis of phytoplankton proceeds normally.

3. When using cages for overwintering 1-year-old fingerlings, change the open-top type to a closed type, remove the feeding platform inside the cage, and sink the cage to the bottom of the pond (ditch). At the same time, the water depth of the pond (ditch) should preferably be 50 cm higher than the top of the cage. Pay attention to promptly clearing the snow on the ice surface after snowfall so that the ice surface transmits light well.

4. After the beginning of spring, during spring weather with low temperatures and continuous rain and sudden cold and hot changes (frequent arrivals of cold air), algae in the pond are prone to mass death, water quality deteriorates, and in severe cases the water even becomes foul-smelling, causing severe oxygen deficiency. When this happens, new water should be added or the water changed in time. Quicklime (20 to 30 kg/mu) can be periodically slaked in water and splashed over the whole pond, which can sterilize and disinfect, coagulate suspended matter, and has a certain effect on regulating water quality.

3. Doing a good job of fish disease prevention and control

Prevention first, combining prevention and control. During the farming process, some water quality improvers, substrate improvers and microbial preparations are often used; using them together with live bacteria works better and gives better water quality. Regularly disinfect the farming water body, sterilize and kill insects, and cut off the horizontal transmission of pathogens. It is best to use disinfectants that are non-irritating to fish and leave no toxic residue (such as bleaching powder, table salt, quicklime, Yujunjing, Yujunqing, etc., and Chinese herbal medicines). Regularly feed medicated bait to strengthen the fish's constitution and improve their ability to resist disease and cold and overwinter. Overwintering fish ponds should remain quiet to prevent poultry and livestock from falling into the pond and causing fish to become restless. To avoid the occurrence of water mold and dead fish, minimize fishing or transferring between cages during the overwintering period.

Living habits of snakehead fish  

1. Snakehead fish are wild fish, found in many rivers, lakes, reservoirs, streams, ponds and ditches in both southern and northern China. In some places in the south, they are also specially stocked by humans, but only in separate ponds. If a few snakehead fish get into someone's fish pond, the fry in that pond will certainly suffer. Snakehead fish are fierce and aggressive and have long been known as the "overlord of the water"; they are truly a scourge to fish ponds.  

2. Snakehead fish are ferocious carnivorous fish. In the juvenile stage, they mainly eat zooplankton in the water; as adults they specialize in eating small fish, small shrimp, aquatic insects, loaches and small frogs.  

3. They have extremely strong vitality, tolerate low oxygen, and have strong adaptability to the environment. Individuals are large and grow quickly; the maximum body length can reach 2 m, and body weight can reach 100 kg. After pond water dries up, snakehead fish burrow into wet mud and can survive for two to three months without dying; once there is water again, they can revive as if nothing had happened.  

4. They are middle- and lower-layer fish and often hide in crevices between stones, quiet places, or places overgrown with weeds, waiting for an opportunity to catch prey. In summer they often come to the water surface to bask in the sun; in winter they dive into the bottom mud layer or among wormwood residue to overwinter.  

5. Snakehead fish like to inhabit lakes, reservoirs, rivers, ditches and ponds with lush aquatic plants and soft muddy substrate. Ordinarily they lurk at the bottom and only move to the middle and upper layers of the water body when feeding or when oxygen in the water is low. Snakehead fish have relatively strong adaptability to poor water quality, water temperature and low oxygen. In addition to gills, snakehead fish also have an auxiliary respiratory organ (the suprabranchial organ); when oxygen in the water is low, they can stick their heads out of the water to breathe oxygen from the air directly.

How to farm snakehead fish  

1. Pond selection  

The pond for farming snakehead fish should not be too large; generally an area of 0.2 to 0.33 hm2 is good. The pond water depth is 1.5 to 2.0 m, the bottom mud thickness is 15 to 20 cm, the water source is sufficient, and drainage and water injection are convenient.  

2. Fingerling stocking  

The size of the fingerlings stocked is determined according to the size of the market commodity fish. At present, snakehead fish with an individual weight of 0.7 to 2.0 kg sell well, so the size of fingerlings stocked should be 75 to 100 g per fish. The stocking density should be determined according to factors such as feed sources and farming techniques; generally 2000 to 2500 fingerlings are stocked per (667 m2). At the same time, 400 to 500 bighead carp fingerlings can be stocked together, with a fingerling size of 100 to 150 g per fish.  

3. Feed feeding  

Snakehead fish are ferocious carnivorous fish; they eat both live food and dead food, mainly feeding on wild trash fish such as small crucian carp. In artificial farming, a method of feeding at fixed times and fixed locations with domestication is adopted. Feed twice a day, at 10 a.m. and 3 p.m. Generally, after 5 to 7 d of stocking, all the fingerlings can float to the water surface to compete for food. When feeding, carefully observe the feeding situation of the snakehead fish near the feeding platform. If there are few snakehead fish near the feeding platform and competition for food is not intense, it indicates that the fish are already full and feeding can be stopped.  

4. Feeding management  

Snakehead fish have a large appetite and produce a lot of excrement, which can quickly make the pond water fertile. Fertile water can cause plankton to multiply greatly, which can easily cause oxygen deficiency in the pond water. Therefore, special attention should be paid to changes in dissolved oxygen in the water. Once oxygen deficiency occurs, turn on the aerator in time. If the oxygen deficiency is relatively severe, a partial water surface killing method can be adopted, that is, splash trichlorfon on the water surface 2 to 3 m from the pond bank, at a concentration of (0.5 to 1.0)×10-6. 

Farming benefits of snakehead fish  

Snakehead fish have a well-developed auxiliary respiratory organ, tolerate low oxygen and fertile water, and will not die after being out of water for a long time, making them suitable for high-density farming. Snakehead fish farming has high yields and significant economic benefits. Generally, the yield of snakehead fry and fingerlings is about 750 kg/67 m2, with an output value of about 13,500 yuan; the yield of adult fish is about 450 kg/67 m2, with an output value of about 7,200 yuan.  

How much profit snakehead fish farming makes mainly depends on the market price of snakehead fish, the price of bait, and whether the farming is successful. For snakehead fry and fingerling cultivation, generally expanded pellet feed is fed, and the cost per kg of weight gain is about 10.5 yuan, including water and electricity, fish medicine, feed, etc., and the feed conversion ratio is about 1; when feeding bait fish, the feed conversion ratio is generally 3 to 4. The size of the feed conversion ratio mainly depends on the quality of the bait fish, and the cost per kg of weight gain depends on the market price of the bait fish, which fluctuates greatly. Adult fish farming generally feeds bait fish, with a feed conversion ratio of 3 to 4, and the cost per kg of weight gain is the same as in the fingerling case.  

In short, the economic benefits of snakehead fish farming are not unchanging. The benefit of snakehead fry and fingerling cultivation is generally about 5,000 yuan/67 m2, and the benefit of snakehead adult fish farming is generally about 1,500 yuan/67 m2.

No matter what kind of thing is farmed, it is very necessary to master its living environment. Only by mastering its living environment can we create a water area suitable for them to live in. Only then can we continuously update existing technology, develop the farming business bigger and bigger, and make the road of farming broader and broader.