Study on artificial breeding technology of cultured Takifugu ocellatus

Objective The study aims to analysis the growth, reproduction, and gonad development of T. ocellatus under artificial breeding conditions. Methods The growth and gonadal development of artificially bred T. ocellatus F₁ were observed by three-year artificial culture, and the effects of different salinity (0, 5, 10, 15, 20, 25, 30) on the fertilization and hatching of mature eggs of T. ocellatus F₁ were studied during the breeding season. Results 1) the body mass was (55.4 ± 14.6) g at one year old, and (105.9±25.8) g at two years old, and (148.0 ± 35.5) g at three years old under freshwater rearing conditions; most individuals could develop to sexual maturity at two years old. 2)_ T. ocellatus reproduces once a year in the Zhangzhou area of Fujian, and the breeding time is from early October to mid-November. The gonads of female fish can develop to stage IV from 2 to 3 year old in freshwater culture conditions, but they cannot naturally ovulate. Female broodstocks could obtain physiologically mature eggs after injection of the hormone HCG or LRH-A. 3) salinity has a significant effect on the fertilization of mature eggs and hatching of fertilized eggs of T. ocellatus. When the salinity is 0, mature eggs cannot be fertilized, and fertilized eggs cannot be hatched; when the salinity is 5.0 and 10.0, the fertilization rate and hatching rate are 78.6%, 94.4% and 7.6%, 31.3%, respectively. 4) the eggs of T. ocellatus are adhesive eggs, and that of the diameter of egg after water absorption and expansion is 1.131 to 1.163 mm. The absolute egg production is (1.92－6.25)×10⁴ eggs of female broodstocks which body mass from 82.3 g to 115.7 g. It takes 5－6 days from fertilized eggs to the hatching of fry under the conditions of salinity 20 and water temperature 20.2－25.5℃. Conclusion The successful full-artificial breeding of T. ocellatus can initially solve the problem of seedling sources, and also lay a foundation for the research on the artificial mass breeding and the release of wild resources.