From April to December, 2012, a total of 583 specimens (rabitfish, Siganus rivulatus) were collected at random from the mixed catch of the Bardawil lagoon. Monthly, total length, total weight, and the weighing of gonads were recorded. The specimens were sexed with naked eye. Bymonthly variation of the Gonadosomatic index values, the higher values were recorded in June, July and August with a peak in June where spawning season. The sex ratio was 1:1 around the year with slightly change of ratio month by month between females to males. The length at first maturity was estimated at 13.8 cm and 14.4 cm for female and male respectively. The absolute fecundity was calculatedas fish of 14.4 cm (41.5 g.) to lay eggs about 57244 reaching maximum of about 356410 eggs for a fish of 21.6 cm (149 g.). The relative fecundity gradually increased from 1228 to 2392 eggs per gm with average of 1798 g^-1. Prevent fishing craft Shrimp (Al kalssa) in the months of June to July, where spawning season of S. rivulatus in the Bardawil lagoon.