On December 13, 2010, Zhou Huishan of Rudong County called the newspaper “Fishing Technology 110†to report that he had about 4 mu of water in his home. Some stingrays were collected from natural waters. In 2011, he wanted to breed stingrays on his own. For high-density pond culture, he asked: How do the male and female stingrays judge and how to incubate their seedlings?
The reporter interviewed Cai Yongxiang, a senior engineer of the stingray breeding expert of the Jiangsu Provincial Freshwater Fisheries Research Institute. Cai Yongxiang said that the artificial breeding of stingrays is generally conducted from May to June, when the water temperature is 20 to 30°C, and is usually carried out in concrete tanks. There are also a small number of farmers operating in cages, but the rate of emergence of cement pools is higher than that of cages.
It is known that there is no significant difference between male and female fish observed from the external morphology before sexual maturity, and individual differences after sexual maturation are significant. Generally in sexually mature individuals of the same age, males are larger than females, males have an apparent genital process behind the anus, and females do not. The male body is elongated, the female body is thick and short, the abdomen is inflated and soft, and the genital hole is red and swollen. In the first half of the year, the proportion of males in the broodstock collected from natural lakes is greater than that of females, and in the mature broodstock collected from natural lakes in the second half of the year, the proportion of females is greater than that of males.
What kind of stingray is suitable for spawning? Cai Yongxiang said that in the breeding season (May-June), carefully observe the broodstock's abdomen, and the sexually mature broodstock is fuller in abdomen and feels softer. In addition, according to the broiler's body weight can also be determined, generally should choose more than 100 grams of weight/tail of the broodstock, pond breeding ratio of 3 to 5:1.
"It is unscientific if the brooder is only allowed to breed naturally in the pond (spawning, fertilizing, and emergence)." Cai Yongxiang said that the seedlings propagated in this way have a low rate of emergence and survival. The number of seedlings is also relatively small, because the produced eggs and fry can easily be fed by the broodstock, so full artificial breeding should be carried out during the production process. First of all, injecting oxytocin into the stingray to promote its gonad maturation. After the broodstock is put into the pond with microfluidic water in proportion, the seedlings are grown and put into the fish nest. When the brood fish chase each other, the broodstock will be caught. The egg is squeezed into a ceramic bowl and the male fish is killed. The testicles are removed, cut into pieces and feathered and poured onto the fish nest. In addition, after the broodstock has played oxytocin, it is put into the pond in proportion to allow it to spawn, and the broodstock or the nest are promptly removed after the spawning is completed.
The growth and development of fertilized eggs is best carried out under microfluidic conditions. Cai Yongxiang said that “spawning eggs†is the best method to determine if eggs are fertilized. Since fertilized eggs have a certain viscosity, unfertilized water can flow through the flowing water. Egg shake off, in addition can also maintain a good breeding environment for the pond water body, promote the fertilized egg out of the membrane (in the microfluidic state, the fertilized egg can generally be filmed in 3 days).
After the film is hatched, due to the smaller seedlings, it is best to feed live rotifers, red worms and other feed (pond fertilizer production). If the pond culture conditions are good, the fry can be divided into ponds after 3 to 5 days of culture. .
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