| 【Objective】This study aimed to understand the effects of exogenous human chorionic gonadotropin（HCG）hormone inducing ovulation of the blacktip grouper（Epinephelus fasciatus）.【Method】The mature E. fasciatus was used as the target object, and the body length, body weight, and condition factor were measured and calculated. After that, 6 female fishes were injected with HCG（dosage: 200 IU/kg or 500 IU/kg）from July to August in 2018 to conduct maturation induction.【Result】Under the 200 IU/kg HCG treatment, before 24 h of the HCG injection, the tertiary yolk stage 1（Ty1）was detected in oocytes of 5 female fishes. After 48 h of injection, the migratory nucleolus oocytes were found in 2 female fishes, and the tertiary yolk stage 2（Ty2）was detected in oocytes of 1 female fish. After 60 h of injection, the ovulation phenomenon was observed in 1 female fish, and the Ty2 was found in other 5 female fishes. In the ovulation individual of 200 IU/kg HCG treatment, the oocyte diameter was 477.0 μm during the injection while it increased to 624.4 μm after 60 h of injection. Furthermore, after the steps of injection, ovulation, fertilization and hatching, the total number of eggs obtained was 16906, and the fertilization rate and hatching rate were 68.7% and 43.0%, respectively. However, the ovulation of E. fasciatus was
not observed in the 500 IU/kg HCG treatment. 【Conclusion】In conclusion, the 200 IU/kg usage of exogenous HCG hormone treatment may induce the maturation and ovulation in the blacktip grouper. However, to improve the fertilization rate and hatching rate, the injected dosage and effective time should be further regulated. |
