Artificial propagation and incubation technology of Shiping silk-tailed turtle in Yunnan
Yang Yi
Silktail turtle, commonly known as the white bearded gong, commonly known as the "long beard fish", belongs to the catfish, catfish family, catfish genus, is an indigenous fish in the Lancang River system, mainly distributed in the lower reaches of the Lancang River tributaries in Yunnan Province. Because of its tender meat, good taste, no intermuscular spines, deeply loved by consumers; and because of its wide adaptability, strong disease resistance, low oxygen resistance, high economic benefits, it has been respected by the majority of farmers, at present, in Yunnan Xishuangbanna, Lincang and Pu'er and other places have begun to take shape.
1 Induced reproduction
1.1 Broodstock rearing and selection
The sexual maturity age of captive-reared silk-tailed turtles is generally 3 winter age, and the breeding season in Xishuangbanna is 6-7 months, and spring is the fastest period for broodstock gonads, and feeding should be strengthened. Broodstock are fed special feed, fresh fish or fish offal, the amount of feeding is 2% of the body weight of the broodstock, and for some time before childbirth, the male and female broodstock are polycultured in often filled broodstock ponds to promote their gonadal development. Females with enlarged, soft, elastic and ruddy genital foramen were selected as parents, while male parents had protruding, tapered genital foramen, dendritic nests, and squeezed semen from the genital foramen to be difficult to flow out. The ratio of male and female broodstock is 1 to 3.
1.2 Injection of oxytocin
The oxytocin is injected in 2 sessions at a shallow depression at the base of the pectoral fin. Oxytocin is LRH-A2, DOM, and carp pituitary gland, etc., and is used after preparation with normal saline. The first injection dose was LRH-A22 μg + DOM 3 mg/kg for females and LRH-A211 μg + DOM 4 mg + HCG1000 IU/kg for males, halving for males.
1.3 Artificial insemination
Dry insemination is performed in a cool place. In order to improve fertilization and survival rates, breeding is selected at 3:00 a.m. Artificial insemination requires killing the male to extract sperm, and the male semen nest is removed and placed in a mortar to be cut and ground. 1 person gently lifted the female broodstock, the other 1 person wiped the water on the fish with a dry towel, gently pressed the female fish abdomen to squeeze out the eggs in a dry plastic basin, mixed the broken sperm nest with normal saline with gauze and immediately poured into the plastic basin, gently stirred with feathers, so that the egg cells and sperm were fully mixed and fertilized, let stand for 2 to 3 minutes and then evenly poured on the incubation mesh, and finally moved into the incubation pool for incubation.
2 Artificial incubation
After the fish eggs are fertilized, the fertilized eggs are slowly and evenly poured on the hatching mesh, the density should be uniform and appropriate, do not overlap, and after the eggs are glued, the mesh is hung with wire in a rectangular cement pond for incubation. Maintain proper water flow and uninterrupted inflation during incubation, while avoiding strong light on the eggs, gently shake the mesh every 2 h, so that the unfortilized eggs and sand in the water are separated from the mesh, so as to keep the environment around the fertilized eggs on the mesh clean and conducive to improving the hatching rate.
At water temperature of 28 ~ 32 °C, the fertilized eggs hatch out of the membrane after 28 ~ 30 h, and the newly out of the membrane is 3 mm long, the swimming ability is poor, the whole body is transparent, the yolk sac is large, nearly round or oval; The swimming ability of the 3rd day of the membrane is significantly enhanced, and the yolk sac is basically absorbed and begins to forage, and the harvest worms are fed as open bait.
3 Summary
Broodstock before the advent of the spawning season to take fattening to strengthen breeding, spawning season feeding, minimize the content of fatty substances, increase protein, vitamins and other nutrient feeding, enhance broodstock immunity; to cultivate special ponds, choose quiet ponds, to avoid people often walk around interference.
The promotion of artificial breeding technology of silktail turtle has brought hope to fishery farmers, expanded the scale of breeding, increased production, and improved economic benefits. However, in the breeding season, because the male semen can not be squeezed out, it is necessary to cut the abdomen to extract the sperm nest, resulting in the waste of male fish, to a certain extent, to bring different degrees of economic losses to fry producers, breeding costs greatly increased, resulting in fry out of the pond price is several times higher than the general fry.