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Abstract
The present study was to investigate the effects of different HCG concentrations on the reproductive performance of Wallago attu. Matured female broodstock was injected with five dosages of HCG: 1,000, 2,000, 3,000, 4,000, and 5,000 IU/kg. Males were injected with a concentration of 1,500 IU/kg. Additionally, a group of broodstock was injected with physiological saline and used as a control (ĐC). The results of this study showed that the oocyte diameter of W. attu ranged from 1.67 mm to 1.71 mm, and the average distance between the germinal vesicle and the edge of the oocyte ranged from 0.21 ± 0.05 mm to 0.22 ± 0.03 mm, indicating that the fish were capable of participating in spawning. In the broodstock from the control group, no ovulation was observed within 24 hours after the injection. The reproductive stimulation of W. attu females with a dose of 4,000 IU HCG/kg gave the best results, with a 100% ovulation rate, 87.4% fertilization rate, 84.5% hatching rate, and a fry yield of 63,000 individuals/kg of female fish participating in spawning. The embryo development time of W. attu ranged from 18 to 20 hours. The fry consumed all the yolk and started using external food after 2.5 to 3 days.