The complementary effect of melatonin in accelerating ovulation and spawning of the Javaen barb Systomus rubripinnis (Valenciennes 1842).

The Javaen barb Systomus rubripinnis is an endemic fish not domesticated in Indonesia. This study aims to evaluate the effectiveness of gonadotropin and melatonin hormones in inducing ovulation of female Javaen barb. A total of 12 female fish (BW: 142.12 ± 18.08 g; egg diameter 1.0-1.2 mm) were selected to be injected with a combination of different hormones. The treatments were ovaprimTM at a dose of 0.6 mL/kg without melatonin (L0.6M0), ovaprimTM at 0.3 mL/kg with 0.25 mg/kg melatonin (L0.3M0.25), 500 IU/kg of human chorionic gonadotropin with 0.25 mg/kg melatonin (H500M0.25), and 0.25 mg/kg melatonin (M0.25). The L0.6M0 and L0.3M0.25 treatments were injected twice. The first injection was 40% of the total dose, while the rest (60%) was injected 6 hours after the first injection. Melatonin injection was carried out at the same time as the first injection. In the H500M0.25 treatment, melatonin injection was carried out 24 hours after HCG injection. Fish injected with ovaprimTM with and without melatonin had the fastest latency period, and ovulation occurred in all fish. The H500M0.25 treatment had an ovulation rate of 66.7%, while those injected with only melatonin (M0.25) did not ovulate. The number of ovulated eggs, fertilization and hatching rate from ovaprimTM injected broodstock were higher than those of HCG. In contrast, the larvae's survival rate, body weight, and length were similar. In conclusion, ovaprimTM is practical in inducing ovulation of Javaen barb, and melatonin has a complementary effect on Javaen barb ovulation.