Sillago sihama is one of the most common recreational and commercial species in the local fishery in the Persian Gulf and Oman Sea. Various aspects of the reproductive biology of the S. sihama are studied to describe gonad development, spawning season, sex ratio, ovarian histology and fecundity. A total of 676 fish with a total length of 10.44-25.4 cm (Males), 11.17-24.8 cm (Females) and the total body weight ranged between 11.86-124.53 g (males) and 13.96-114.05 g (females) were used for this study. Sex ratio defined as the proportion of females to males was 1.2:1; microscopic and macroscopic gonad analysis and monthly variation of GSI in female component of the S. sihama shows a reproductive season from April and May and continued until June. The ova diameter frequency distributions in mature component indicated that the species exhibits a synchronous-group and monocyclic ovary characterized by deposition in a single batch of eggs per year (total spawner). The size at which 50% of the population attain sexual maturity (Lm50) is 138 mm for females and 132 mm for males. Maximum absolute fecundity is estimated to lie between 21345-73781 eggs for specimens between 13-24 cm in total length and 14.01- 110 g body weight. Relative fecundity was 384.29-832.65 eggs per g body weight. There was a linear relationship between absolute fecundity and fish size for all Species tested.
