To determine the effective LHRH-a dosage for cultured tawny puffer ovulation, the effects of 10, 30, 50, and 70 μg kg−1 body weight (BW) LHRH-a were tested with two injections in 2009, and by a single injection (5, 10, 30, 50, and 70 μg kg−1 BW) in 2010. Ovulation success and egg quality were assessed. All females spawned after being treated with 10 to 70 μg kg−1 BW LHRH-a in 2009 and 2010. Ovulation success was only 20.0% with the 5 μg kg−1 BW treatment, significantly lower (P < 0.05) than in the other treatment groups. No females injected with physiologic saline spawned in the control groups in 2009 and 2010. There was no significant difference (P > 0.05) among the 10, 30, 50, and 70 μg kg−1 BW treatment groups in terms of ovulation success, ovulation time, egg production, fertilization rate, hatch rate, and viability of 24 h post-hatch larvae in 2009 and 2010. None of the treatments caused any mortality among the females during the experimental periods. Results suggest that the treatment using only LHRH-a effectively and reliably induces ovulation in cultured tawny puffer broodstocks, whether through a single injection or through two injections. Effective and most economical dosage of LHRH-a is 10 μg kg−1 BW. Determination of the effective LHRH-a dosage is an important step in the development of tawny puffer fish culture.