Induced spawning is used to solve failure of complete oocyte maturation and fish spawning in captivity. Hormonal inductions with luteinizing hormone releasing hormone analogue (LHRH_a) were examined to induce synchronized ovulation and improve spawning of wild-caught rabbitfish, Siganus rivulatus. Three experiments were carried out to study their impact on egg quality. Experiment I: LHRH_a intramuscular injections of 50 and 100 µg kg^-1 were used for two different groups respectively with a third control group. Experiment II: LHRH_a injection (100 µg kg^-1) was used to study the impact of both spontaneous spawning and stripping methods. Experiment III: LHRH_a injection (50 µg kg^-1) was used to study the influence on sex ratios. Two successive injections (LHRH_a) were used for females in all experiments while male fish received only one dose. In experiment I, the response to higher dose showed a significant increase (p < 0.01) in egg diameters, latency time, total number of spawning fertilized eggs and hatching rate. In experiment II & III, a significant improvement (p < 0.01) was observed in all egg quality parameters with both spontaneous spawning and sex ratio (2 male:1 female). LHRHa injection is an adjunct to improve spawning performance and Siganus rivulatus culture production.