A Detailed Explanation of the Latest Scientific Techniques for Snakehead Farming

When we talk about snakehead fish, we cannot help but mention its tender flesh and nutritional value, which are now extremely sought after by consumers. So, many people, seeing how popular snakehead fish is, get the idea of farming it. After all, there are not yet many farmers raising snakehead fish on a large scale, so the competition is not very intense either.

The Latest Scientific Snakehead Fish Farming Techniques

Snakehead fish have strong environmental adaptability and low requirements for pond water quality, and can be farmed at high density. Each mu of pond can be stocked with 8000 to 10000 fingerlings, and the yield can reach 4000 to 5000 kg. Snakehead fish grow quickly, and fry from early spring can be raised into marketable fish within the same year. Snakehead fish have few diseases, a high survival rate, and adult fish are simple to transport, making long-distance sales convenient.

1. Broodstock selection: Mid-May each year is the breeding season for snakehead fish. Mature, robust male and female snakehead fish should be selected as broodstock at a ratio of 1:1. The method for distinguishing male from female is as follows: the abdomen of the female snakehead is enlarged and soft, appearing black and white, with an obvious ovary outline, a groove appearing in the center, and the genital pore protruding, pink in color; the male snakehead has a purplish-red body color, with neat rows of transparent small white round spots arranged from bottom to top on the dorsal fin, a darker abdomen, and a slightly enlarged, slightly concave genital pore that is triangular in shape and pale pink. Before induced spawning, place the female and male fish separately in net cages to rest quietly for one day without feeding them, which is more conducive to spawning.

2. Broodstock induced spawning: The female fish is injected twice; the first injection is 1/3 of the total dose, and after an interval of 18 to 26 hours, the remaining dose is injected all at once. The dose for the male fish is half that of the female, and it is injected at the time of the female's second injection. Most fish are injected via the chest cavity, at a 45° angle to the fish body, with the needle inserted to a depth of about 1 cm. Commonly used hormone types include carp and crucian carp pituitary, with a dose of 4 to 8 per kg for female fish and half that for males; or human chorionic gonadotropin, with 16000 to 24000 international units per kg for female fish and half that for males.

3. Egg incubation

① Artificial simulation of the natural environment for incubation: After injecting the induced spawning agent, place males and females in a pond at a 1:1 ratio and let them spawn, fertilize, and hatch naturally. After the fry hatch, take advantage of the snakehead's parental care behavior and let them tend the fry freely. This method saves labor and time; the drawback is a low fry survival rate and uneven growth and development.

② Artificial net cage incubation: After induced spawning injection, place males and females at a 1:1 ratio into 4 to 6 sq m net cages to spawn and fertilize, then remove the broodstock and place them into a large pond. Place the eggs into 40-mesh net cages, with 10000 fertilized eggs per cage, and incubate using a micro-flow water method. The hatching rate depends on the fertilization rate and water quality. At 22 to 27°C, it takes 32 to 48 hours. Check frequently and promptly remove unfertilized eggs.

4. Fry and fingerling rearing: Before hatching out to 2 cm, they should be placed in net cages made of 40-mesh net cloth with specifications of 1 m × 0.5 m × 0.5 m, at a density of 2000 fish per sq m. Four to five days after hatching, feed rotifers or cladocerans, copepods, etc., using a small-and-frequent method, once every 4 hours, for 3 to 4 days; afterward increase the feeding amount and reduce the frequency, gradually transitioning to twice a day. When the snakehead fry reach 2 cm, transfer them to net cages made of 8- to 16-mesh summer-fry net cloth, with an area of 10 to 15 sq m, preferably rectangular, at a density of 500 to 600 fish per sq m

5. Feeding bait: The bait is mainly zooplankton. At 4 to 5 cm, feed minced fish meat plus zooplankton. To prevent debris and filamentous algae from clogging the mesh, brush and wash once a day, change cages once a week, and thoroughly disinfect the net cages.

The Feeding Characteristics of Snakehead Fish

A ferocious carnivorous fish, and rather gluttonous. The prey it captures varies with the size of the fish body. Fry

with a body length under 3 cm mainly feed on copepods, cladocerans, and chironomid larvae, etc. Fry with a body length under 3 to 8 cm feed on aquatic insect larvae, tadpoles, small shrimp, young fish, etc. Adult fish with a body length over 20 cm prey on various small fish and frogs (small fish mainly refers to crucian carp, hemiculter leucisculus, squaliobarbus curriculus, loach, and various juvenile fish). Snakehead fish swim slowly [2], but when hunting they generally do not chase prey; instead, they hide near aquatic plants or other concealed objects and watch the movements around them intently. Once they find suitable live bait such as fish passing nearby, they strike quickly and capture it in one go. Snakehead fish have a large food intake and can often swallow live bait about half their own body length, and the maximum capacity of their stomach can reach around 60% of their body weight. According to dissection, a 500-gram snakehead fish swallowed 8 grass carp fingerlings 10 cm long in a relatively short time. Snakehead fish also have the habit of cannibalism and can swallow individuals of the same species less than two-thirds of their own body length. The size of their food intake is closely related to water temperature. In summer when the water temperature is high, they are quite gluttonous and have a large food intake; when the water temperature is below 12°C, they stop feeding. Under artificial rearing conditions, when animal feed is insufficient, they can also feed on artificial compound feed such as soybean cake, rapeseed cake, and fish meal.

The Reproduction of Snakehead Fish

The spawning season varies depending on the climate conditions of different regions. In South China, it is from mid-April to mid-September, with May and June being the peak; in the central region, it is from May to July, with June being relatively concentrated. The breeding water temperature is 18 to 30°C, and the optimum water temperature is 20 to 25°C.

The age of sexual maturity also differs slightly in different regions. In South China, fish that are over 20 cm in body length and have passed 1 winter have already matured their gonads, while in the Yangtze River basin area, they need to have passed 2 winters and be about 30 cm in body length to spawn. The snakehead can reproduce naturally in waters such as ponds, ditches, and reservoirs, and spawning grounds are generally distributed in shallow water areas with lush aquatic plants. The number of eggs carried and the number of eggs spawned are related to the size of the parent individuals. The snakehead usually carries about 20000 to 30000 eggs per kg of body weight. A 0.5 kg spotted snakehead generally spawns 8000 to 10000 eggs, with individual cases reaching 11000 to 12000 eggs. The spawning method is the nest-building type. Before spawning, sexually mature male and female broodstock swim in pairs at the spawning ground, jointly using their mouths to take aquatic plants and plant fragments and spitting foam to build a fish nest that is roughly ring-shaped, about 0.5 to 1 m in diameter, and floating on the water surface. After the nest is built, on a calm morning before sunrise, the female and male fish chase each other and become aroused, then the female fish, below the fish nest and close to the water surface, turns her abdomen upward in a supine position, her body slowly swaying as she lays eggs onto the nest. At the same time, the male fish releases sperm there in the same posture.

Disease Prevention and Control in Snakehead Fish

The prevention and control of snakehead fish diseases should adhere to “prevention first”, and throughout the entire farming period, the water body should be disinfected regularly. One month after the fingerlings are put into the pond, disinfect once, and thereafter disinfect once every half month. Disinfection drugs include: dibromohydantoin, chlorine dioxide, quicklime, bleaching powder, etc., and the amount used is determined according to water quality conditions and the drug instructions. Regularly add vitamins, allicin, Sanhuang powder, etc., to the bait, which helps enhance the constitution and disease resistance of snakehead fish. During the farming period, pay more attention to observation, and promptly take effective prevention and control measures when an outbreak is discovered.

Now no matter what is being farmed, there are risks, and one must devote full effort to raising and tending them. When farming snakehead fish, the costs are actually relatively high, so during the farming process, special attention must be paid to the prevention and control of snakehead fish diseases. Otherwise, economic losses caused by poor management would mean the loss outweighs the gain.