Detailed Explanation of Key Points for Intensive Snakehead Farming Technology
The northern snakehead is commonly known as snakehead, spotted snakehead, ink-head fish, etc. At present, the main species farmed in China are the northern snakehead, the spotted snakehead and their hybrids. The northern snakehead is a valuable economic fish among the Channidae, with large individuals, fast growth, high yield and high economic value; its flesh is delicate and delicious, with few bones and plenty of meat, it grows relatively fast, and it has high nutritional value. In addition, the northern snakehead has strong adaptability, grows rapidly and is convenient to transport. In recent years, with the development of the domestic aquaculture industry and the needs of foreign trade, the northern snakehead has gradually become a special aquaculture species with strong demand in both production and sales, and is deeply welcomed by farmers.
1. Pond conditions The pond should be chosen next to a reservoir with abundant water, neutral or slightly alkaline water quality, fresh water and no pollution; the pond is rectangular, convenient for drainage and irrigation, with an area of 2000 sq m, an average water depth above 1.2 m, a maximum depth of up to 2 m, and a 10 cm thick layer of silt left at the bottom of the pond.
2. Preparatory work (1) Before stocking, drain the pond water, level the pond and reinforce the slopes, remove excess silt, and let the pond freeze and dry for a period. 10 days before stocking, spread 100 kg of quicklime per 667 sq m for dry disinfection. 5 days later, add new water. (2) In late April, plant aquatic plants such as water hyacinth in the shallow water areas around the pond; after the aquatic plants grow, the covered area should not exceed 25% of the total water area, so as to provide hidden shelter for the northern snakehead and help improve water quality and lower water temperature in the hot season. (3) The northern snakehead is lively by nature, so the pond should be surrounded with bamboo fences, nylon nets and other materials to a height of more than 50 cm to prevent the fish from jumping out of the pond.
3. Selection and stocking of fry and fingerlings (1) Fingerling selection. Choose fingerlings that are uniform in size, smooth on the body surface, plump in muscle, free of injury and disease, lively in swimming, and aggressive in competing for food. (2) Stocking time and size. There are 2 sizes of fingerlings for monoculture of the northern snakehead in ponds: one is large-size fingerlings of more than 50 g each, which should be stocked in early winter; the other is small-size fingerlings of 60 to 200 per kg, which are bred from fry propagated in early spring of the same year after about 2 months of rearing, and should be stocked in June to July. (3) Stocking density. Stock 4000 to 5000 fingerlings per 667 sq m.
4. Feed feeding The northern snakehead is a carnivorous fish. At present, artificial farming of the northern snakehead mostly feeds live bait such as small fish, small shrimp, snails and mussels. When artificially feeding live bait, pay attention to freshness and cleanliness, and soak it in 6% to 8% salt water for 10 to 15 minutes before feeding; the feeding amount is 6% to 8% of the fish body weight. Feed two or three times a day at fixed times and in fixed amounts. If fish and shrimp are insufficient, other animal by-products (such as livestock and poultry viscera) can also be fed; the by-products must be fresh and clean, chopped when fed, and disinfected. Artificial compound feed can also be prepared according to the nutritional needs of the northern snakehead to supplement the shortage of live bait.
5. Water quality management In high-density farming, due to the large amount of residual bait and excrement, the water quality is prone to turning black and foul, affecting the healthy growth and quality of the northern snakehead and also causing disease outbreaks; comprehensive measures must be taken to control water quality: first, change water frequently; in the early and late stages of farming, change water once every 5 to 7 days, and from July to September change water once every 4 days, each time changing 30 cm of depth. Second, use biological agents, such as regularly using photosynthetic bacteria to engulf harmful bacteria. Third, turn on the aerator in a timely manner to increase oxygen and aerate, promote the decomposition of harmful substances such as hydrogen sulfide and ammonia nitrogen at the bottom of the pond, and keep the pond water transparency above 35 cm.
6. Disease prevention and control The prevention and control of northern snakehead diseases should adhere to the policy of "prevention first"; throughout the farming period, regularly disinfect the water body. Disinfect once 1 month after the fingerlings are put into the pond, and then disinfect once every half month. Disinfectants include: dibromohydantoin, chlorine dioxide, quicklime, bleaching powder, etc., and the dosage is determined according to water quality conditions and the drug instructions. Regularly add vitamin C, allicin, Sanhuang San, etc. to the bait, which helps enhance the physique and disease resistance of the northern snakehead. During the farming period, pay more attention to observation, and take effective measures in a timely manner to prevent and control outbreaks once discovered.