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Earthen ponds
Eel farming in earthen ponds can achieve high yields, typically ranging from 800 to 1,000 kg per mu annually. The pond area usually spans 1,000 to 2,000 square meters with a water depth of 1.5 to 1.8 meters. Floating plants like water lilies and water peanuts are placed on the surface at intervals of 0.8 to 1 meter, secured by fences or nets. Before restocking, quicklime is applied at a rate of 100 to 125 kg per 1,000 square meters about 10 to 15 days in advance to eliminate wild fish and pests. In the first 5 to 7 days before stocking, seedlings are placed at a depth of 0.6 to 0.7 meters, and the inflow is filtered using a 60-mesh sieve. A base fertilizer of 300 to 400 kg of well-rotted pig or cow manure is added per 1,000 square meters. Once the water turns light green or yellow-brown, the eels are released, and the water level is raised to 1.5 meters after about half a month.
Carp thrive best in water temperatures between 20 and 28°C, and feeding begins when the temperature reaches 12°C. Eel seedlings are typically introduced from late February to mid-March. Before placing them in the pond, the bags should be soaked in water for 20 to 30 minutes to help the eels adjust to the water temperature (bags can be folded if the internal and external temperature difference is less than 5°C). Then, 2 to 3 pots of water are added to the bag to gradually transition the eels from high to low dissolved oxygen levels. Disinfection is done before introduction: mix 0.75 to 1 kg of salt in 50 kg of water and soak for 15 to 20 minutes.
Stocking density varies depending on eel size: 4,000 to 5,000 individuals per 1,000 square meters for 20g eels, 3,000 to 4,000 for 50g, and 2,000 to 3,000 for 100g. To improve yield and water quality, you can also add 50 squid, 30 shrimp, and 200 tilapia per 1,000 square meters.
Feed with commercial compound feed, adding 50 to 60 grams of multivitamin (A, B, C, E) and 1.5 to 2 kg of cod liver oil per 50 kg of feed. However, stop adding cod liver oil when the water temperature is below 20°C or above 35°C. Feed small fry more frequently and larger ones less often. If special feed is unavailable, use animal by-products such as trash fish, poultry organs, or silkworm pupae, ensuring a crude protein content of over 40%. Feeding must be consistent in quantity, timing, and location. Generally, feed 1.5% to 2.5% of the total carp weight daily, and ensure all food is consumed within 12 hours. For smaller sizes, feed 8 times a day—once in the morning and once in the afternoon. Place 2 to 3 feeding trays per 1,000 square meters.
Daily inspections are conducted in the morning and evening to monitor feeding behavior. After rain, check drainage systems to prevent fish escape. Freshwater is added every 10 to 15 days, and water is changed every 5 to 7 days during summer and autumn, replacing 10% each time. Maintain a pH level between 7 and 8.5.
Disease prevention is essential. Every 20 to 30 days, treat the pond with furazolidone (2.5–3 mg/L) and bleaching powder (1 mg/L), applying the treatment for two consecutive days. If mudworms or blisters appear, spray 450–500 g of trichlorfon per 1,000 square meters. Regular monitoring and timely intervention are key to maintaining a healthy and productive eel farming environment.