Detailed Explanation of Techniques for Self-Breeding Rice Field Eel Fry

1. Selection and Cultivation of Parent Eels

Eels used for breeding must have a robust physique and swim actively. The body color is best in coarse black mud, yellow-brown, or black speckled, green-brown. The source of parent eels should be those caught in cages the same day with relatively small wounds.

@#@236@#@ has sex reversal characteristics; 1-winter-age and 2-winter-age rice field eels are basically female, and after 2-winter-age rice field eels spawn, the proportion of males gradually increases, until at 6-winter-age they are basically male. During the non-spawning season, it is difficult to distinguish male from female; generally, body length and body weight are used as standards, generally body length 37-50 cm and weight 75-200 g are male eels, and those smaller than this standard are female eels. For breeding, the ratio of female to male is preferably 2-3:1. During the spawning season, the abdomen of the female eel is enlarged and soft, and in some cases a clear transparent band can be seen on the abdomen, the outline of eggs can be seen outside the body, and the genital pore is red and swollen before spawning.

The stocking density of parent eels is 7 female eels and 2-3 male eels per square meter of water body. The parent eel cultivation pond is about 3 sq m, with a water depth of 25 cm. The pond walls have sufficient irregular holes, and aquatic plants such as water hyacinth are planted in the pond (about 1/4 of the pond area) to provide shade and hiding for the rice field eels. The feed is mainly live @#@254@#@, @#@261@#@, mussel meat or snail meat. Mussel meat and snail meat should have broken shells and opercula removed. The feeding amount is 2.5%-8% of the fish body weight per day, fed once in the evening. In terms of management, residual bait should be removed in time and new water should be added.

2. Eel Reproduction and Fry Cultivation

Rice field eels can reproduce from May to September, with the peak breeding period from June to August. After the parent eels are paired and placed in the pond, cultivation should be strengthened to promote gonadal development. Rice field eels reproduce and spawn in caves, and occasionally in stone crevices near the water surface or among the fibrous roots of aquatic plants. They generally guard until the eel fry hatch. When rice field eels spawn, they spit out a large number of bubbles near the cave. The fertilized eggs hatch into fry after 1 week and are then transferred to a nursery pond for cultivation. When the eel fry hatch, their body length is only 1.1-1.2 cm, and they lie on their sides on the bottom of the water pond, relying on the yolk sac for nutrition. Five days after hatching, they begin to be fed egg yolk (sifted through a 50-mesh sieve); after 3 days, rotifers are added; after 1 week, they are fed water worms and water fleas; after 10 days, minced fish is added; after 20-25 days from hatching, the body length can reach 5 cm, and artificial compound feed begins to be provided, with added earthworm slurry; after 2 months, the body length reaches 7 cm and they can be divided into ponds for rearing; after 120 days of cultivation from hatching, the body length can reach 8-13 cm. The bottom of the nursery pond should have a certain layer of silt. If there is no condition for micro-flowing water, water can be changed once every 2-4 days, each time changing 1/3-1/2. When changing water, the temperature difference between the two locations should not exceed 3°C.