The rice field eel (Monopterus albus) is delicious and nutritious, making it a prized delicacy among fine fish. In recent years, natural wild rice field eel resources have declined, and market demand exceeds supply. Therefore, developing artificial aquaculture of rice field eels has broad prospects. Raising rice field eels in cages requires low investment and yields high output. The aquaculture techniques are as follows:
I. Cage Layout
Ponds, reservoirs, lakes and rivers can all be used for cage culture of rice field eels, requiring a water depth of over 0.7 m and convenient water inflow and drainage. For making cages, polyethylene knotless netting is best. The mesh size should be 0.6 to 1.3 MM, the diameter of the ropes along the top, bottom and four corners of the cage should be 0.8 CM, and the cage should be made into a rectangle. A cage area of 12 to 20 sq m is appropriate; too large is difficult to manage. The cage draft depth is 0.5 m, and the upper edge of the cage should be more than 0.5 m above the water surface.
II. Selecting and Purchasing Rice Field Eel Seedlings
For raising rice field eels, the seedlings are key. Rice field eel seedlings must be artificially bred and domesticated dark-yellow large-spot eels or golden-yellow small-spot eels; mottled eel seedlings and non-domesticated eel seedlings cannot be used, and one should not believe in "giant eels" or "Thai giant eels." The size of rice field eel seedlings is best at 30 to 60 per kg. For cage culture, the stocking density is generally best at 1 to 1.5 kg of eel seedlings per sq m.
III. Feeding Management
1. Cage Preparation and Eel Seedling Stocking
20 days before stocking, clear the pond with quicklime; 15 days before, soak the cage in 20 PPM potassium permanganate for 20 minutes; place water peanut (Alternanthera philoxeroides) or water hyacinth (Eichhornia crassipes) into the cage to grow, letting the aquatic plants cover three-fifths of the cage, and then the seedlings can be stocked.
When stocking eel seedlings, they must be disinfected by soaking in medication; during disinfection, the water temperature difference should be less than 2 degrees. Commonly used disinfectants include: table salt: concentration 3 to 5%, soak for 8 to 12 minutes. Eel Disease Remedy: concentration: 10 to 15 ml of Eel Disease Remedy per ton of water, soak for 15 to 25 minutes.
2. Feeding Feed
After rice field eel seedlings are placed in the cage, do not feed them for 1 to 3 days. From the 4th to 7th day, begin feeding. Feeding at 6 to 7 PM each day is optimal. At this time, the rice field eels' feed intake is highest. For artificial cage culture of rice field eels, compound feed is the main feed, with appropriate feeding of some earthworms, river snails and small trash fish. The feed is placed directly into the aquatic plants in the cage for the eels to consume. For compound feed, Dajiang brand complete rice field eel feed or Changjiang brand rice field eel compound feed can be used. It can also be self-mixed, with the formula: fish meal 21%, cake and meal types 19%, energy feed 37%, earthworm powder 12%, minerals 1%, mother 5%, multivitamins 2%, binder 3%. Using artificially bred dark-yellow large-spot eel seedlings and feeding this compound feed, the feeding amount is 3 to 5% of the eel's body weight.
IV. Preventing Eel Diseases
In cage culture of rice field eels, disease prevention is primary. After the eels feed normally, disinfect the water body once every 10 days. Commonly used drugs include: Eel Disease Remedy, Zhuanliting, Junbijin, Eel Shierkang, etc. Treatment methods for common eel diseases: Hemorrhagic disease: splash Eel Disease Remedy over the whole pond or soak the eel bodies for 30 minutes, with a dosage of 1 to 1.5 ml of Eel Disease Remedy per cubic meter of water. Enteritis disease: mix 30 g of garlic into the feed per 100 kg of rice field eels daily and feed continuously for 3 to 5 days. Do not use drugs banned by the state, such as chloramphenicol and furazolidone.