Key Technical Points for Rearing Snakehead Summer Fry in Cement Ponds
I think many people have eaten snakehead in their lives, and anyone who has eaten snakehead knows that its flesh is very delicious and highly nutritious. Whether braised or stewed as soup, it makes a fine dish. Therefore, in China's aquaculture industry today, snakehead is relatively popular among farmers.
Techniques for Rearing Snakehead Summer Fry in Cement Ponds
1. Cement pond structure and disinfection: The cement pond should be designed to be 5-10 sq m in size and 80-100 cm high, with anti-escape facilities at the inlet and outlet, and the bottom sloping from the water inlet toward the water outlet. Each pond is equipped with a feeding platform, about 20 cm below the water surface, and aeration equipment is installed. A plastic greenhouse is built over the rearing pond to keep the environment relatively stable. When designing the rearing pond, the convenience of operational management and disease prevention and treatment must also be considered.
Before stocking fry, the rearing pond must be strictly disinfected. If it is a newly built cement pond, it must be soaked in clean water half a month to 20 days in advance to remove the alkalinity of the new pond, and then thoroughly disinfected and cultivated until it develops a tender green color. For industrial seedling rearing, the water quality can be cultivated in a reservoir.
2. Stocking density: For still-water rearing, 400-500 fry per sq m. For micro-flow water rearing, up to 600-800 fry per sq m, with the highest reaching 1000 fry per sq m.
3. Feed and feeding methods: Newly stocked fry still feed on live zooplankton. Each 10,000 fry are fed 0.2-0.3 kg of zooplankton per day, but this should be adjusted appropriately according to the actual food intake of the fry. They must be allowed to eat their fill so that growth speed is guaranteed and they develop a strong constitution. Overfeeding will cause zooplankton to compete with the fry for oxygen, and the zooplankton will soon die in large numbers and pollute the water quality, causing fry mortality. After the fry reach 2 cm in length, in addition to feeding live bloodworms, 1-2 bags of dead bloodworms are hung on the feeding platform to begin training them to feed on dead bloodworms. For each 10,000 fry, 500 grams of dead bloodworms are hung, increasing by 300-500 grams every 5 days. If the supply of bloodworms is insufficient, dried yeast, fish paste, etc. can be added to the dead bloodworms as a supplement. Practice has proven that the feeding amount must be sufficient so that the fry eat their fill; then the fry grow quickly and the survival rate is high. Otherwise, the fry will decrease noticeably. When hanging bags for feeding, the amount in each bag should not be large, but the number of bags hung should be greater, so that the fry have more opportunities to eat and grow evenly.
4. Rearing management:
① Water quality regulation: During the fry rearing stage, the dissolved oxygen in the water body should not be lower than 3.2 mg/L. During the cement pond rearing stage, because the area is small, the water is shallow, the stocking density is high, organic matter accumulates heavily, and water quality changes quickly. Therefore, for still-water rearing, water must be changed frequently, 1-2 times per day. Before changing the water, first remove the leftover feed on the feeding platform and siphon the bottom sludge, then change 1/3-1/2 of the pond water. Aerate in a timely manner, and plant aquatic plants on the water surface to improve the water environment.
② Timely grading and rearing: According to actual observation, when the fry reach about 2 cm in length, not only do they differentiate in size, but they also begin to cannibalize one another. This is especially likely to occur when the feed supply is insufficient. Therefore, when the fry exceed 2 cm in length, they must be graded and reared regularly, generally changing ponds once every 7-10 days, and the fry must be screened and graded when changing ponds. After 2-3 gradings, when the fry reach 3-4 cm in length, they can be moved into cages or earthen ponds for fingerling rearing.
③ Strengthen pond patrols: Pay attention to observing the fry's feeding and activity conditions and changes in water quality. If a decrease in food intake is found, along with fry gathering and stagnating at the water surface, slow reactions, swimming alone away from the group, and abnormal body color, attention should be paid. Starting with water quality monitoring, fish body examination, and adjustment of the feeding amount, timely disease prevention and treatment measures should be taken; problems in the production process should be identified and corrected in a timely manner. During pond patrols, also pay attention to whether the anti-escape facilities in all places are intact to prevent fry from escaping.
How to Raise Snakehead Well
1. Pond construction: Choose an east-west oriented, rectangular pond with a mud bottom, a pond depth of 2-2.5 m, and a water depth of 1.5-2 m. Anti-escape facilities must be installed at the inlet and outlet. Apply 100-150 kg of quicklime per mu 15 days before rearing for thorough disinfection.
2. Fingerling stocking: Before the fingerlings are stocked in the pond, soak them in 3%-5% salt water for 10-15 minutes, then put them into the pond. For fingerlings with a body length of 10-14 cm, the stocking density is 9000-10000 fish per mu; for fingerlings of 16-20 cm, the stocking density is 8000 fish per mu.
3. Daily management: Pay attention to observing the snakehead's feeding, activity, disease trends, and environmental changes. In spring, change 4/5 of the pond water each week; in the high-temperature season, change a small amount every 3 days and a large amount every 7 days. Install anti-escape nets at the inlet and outlet, and it is best for the pond embankment to be more than 50 cm above the water surface. The discharged wastewater should undergo necessary wastewater treatment.
4. Feed feeding: The feed for raising snakehead includes artificial compound feed, freshwater or marine small trash fish, and scraps left after livestock and poultry slaughter. Before feeding small trash fish, they need to be sorted to remove fish with hard spines, such as yellow catfish.
The Rearing Cycle of Snakehead
Snakehead fry of the current year are generally stocked from May to July, and the specific time depends on differences in regional air temperature, water temperature, climate, and other conditions.
How long it takes for snakehead to grow to 1500 grams is difficult to determine; this is related to factors such as your rearing technology level and the quality of the feed selected, and it depends specifically on the actual rearing environment. It is recommended that during the rearing process you choose ponds with good conditions, high-quality fry, and good-quality feed for raising them, and that you do a good job in daily management and disease prevention and treatment in ordinary times, so as to shorten the snakehead rearing cycle as much as possible.
If the rearing method is correct, the snakehead rearing cycle is one year of rearing to reach one and a half to two jin.
The Nutritional Value of Snakehead
Snakehead has high nutritional value. It has very good dietary therapeutic effects on physical weakness, hypoproteinemia, malnutrition, spleen-stomach qi deficiency, and anemia. Eating snakehead also has a very good anti-inflammatory effect on wounds. Snakehead itself has relatively coarse flesh, so compared with other fish its taste is not as good and it is not especially tasty to eat, but if snakehead is used to make soup, the flavor is unbeatable!
Snakehead has very strong vitality, and its flesh tastes sweet. It contains large amounts of various minerals such as iron, calcium, and phosphorus, and its nutritional components are also very rich, containing fat, protein, vitamin A, B-group vitamins, and so on. In addition, in every 100 grams of snakehead, the protein content can reach as high as 20 grams, second only to shrimp. Moreover, snakehead is easy for the human body to digest and absorb, and regular consumption of snakehead can enhance resistance.
Although the market demand for snakehead is large and the prospects for rearing are very good, farmers still need to master certain rearing techniques and skills and understand some everyday rearing knowledge, which is very helpful for rearing.