Detailed Explanation of the Key Technical Points for Raising Rice Field Eels in Plastic Greenhouses

Raising rice field eels in plastic greenhouses allows continuous production throughout all four seasons, and soilless flowing-water culture can effectively control disease and multiply the benefits.
I. Construction of breeding ponds:
(1) Open-type breeding ponds, suitable for building ponds in places with flowing water year-round. The breeding ponds are built with bricks and cement, each pond with an area of 10-20 sq m, a pond depth of 40 cm, a width of 1-2 m, and a ridge width of 20-40 cm. At opposite positions in the pond, install 2 water inlet pipes and 2 drainage pipes each with a diameter of 3-4 cm. The water inlet pipes are level with the pond ridge, 1 drainage pipe is level with the pond bottom, and 1 is 5 cm above the pond bottom; all inlet and drainage pipe openings are fitted with metal mesh to prevent escape. Arrange several breeding ponds side by side into 1 unit, and the area of each unit should not exceed 500 sq m.
(2) Closed recirculating filtration-type breeding ponds. Suitable for use in places lacking a water source. The construction method of the breeding ponds is the same as for open-type breeding ponds; in addition, aeration ponds and sedimentation ponds need to be built, along with some water purification, pumping, and heating equipment.
II. Greenhouse construction: The construction of plastic greenhouses is the same as that of ordinary greenhouses; it is best to place each unit in the same greenhouse to facilitate management.
III. Stocking of eel fry: After the ponds are built, plug the main drainage outlet, fill the ponds with water and soak for 5-7 days, then drain the water dry; then plug the drainage pipe that is level with the pond bottom, add water to maintain slight flowing water in each pond at a depth of 5 cm, and then stocking can begin. Before stocking the eel fry, prepare a medicinal solution at a ratio of 8 g copper sulfate and 10 g bleaching powder per cubic meter of water, stir thoroughly, and after the drugs have dissolved, place the eel fry in the solution and soak for 20-30 minutes (water temperature 10-15°C). After disinfection, stock the eel fry promptly, with 4-5 kg of eel fry at a size of 35-50 eels per kg per sq m. The eel fry in the same pond must be uniform in size.
IV. Feed feeding: 2-3 days after stocking the rice field eels, chop earthworms, snails and mussels, frog meat, etc. into pieces, place them in feeding trays for domestication feeding, and appropriately increase the water flow. The first feeding amount can be 1-2% of the total body weight of the rice field eels. Check the next morning; if all has been eaten, the feeding rate for the next feeding can be increased to 2-3%, and thereafter the feeding rate gradually increases to about 5%. As the rice field eels' food intake increases, silkworm pupae, fly maggots, cooked animal offal and blood meal, fish meal, soybean cake, rapeseed cake, wheat bran, rice bran, melon peel, etc. can be mixed into the feed, until completely feeding artificial feed. The protein content of the feed should be 35-40%. Once the rice field eels feed normally, feeding once each day at 8-9 a.m. and 2-3 p.m. is sufficient.
V. Daily management: When raising rice field eels in plastic greenhouses, because the water quality is fresh and clean, as long as the feed is sufficient, the rice field eels generally will not escape, but attention must be paid to preventing harm from natural enemies such as rats and snakes. After a period of rearing, when the rice field eels in the same pond become uneven in size, they must be separated and raised promptly. Rice field eels can be marketed after 5-6 months of rearing, at a size of 6-10 eels per kg, and the survival rate can reach more than 90%.
The most suitable growth temperature for rice field eels is 27-30°C. With plastic greenhouses, there is no need for specially installed heating equipment, and this temperature is easily maintained inside the greenhouse in spring, summer, and autumn. Even in severe winter, the temperature inside the greenhouse can average 20°C. Maintaining slight flowing water in the breeding ponds keeps the water quality from deteriorating.