Sex ratio and reproductive performance of the female crab, Scylla serrata was studied for two years in Coringa mangroves. The crab was a continuous breeder with peak season in winter months (October, November and December). The overall sex ratio of male to female was 1:1.09 with the highest ratio of 1:1.8 in December and the lowest (1:0.84) in May. Males were more in number in the size groups of 2.0-3.9cm, 10.0-11.9cm and 12.0-13.9cm with 1:0.67, 1:0.70 and 1:0.20 male to female ratios respectively. The size at first maturity of female crab was 8.3 cm (carapace length). Gonado-somatic index in female ranged between 3.26 (May) to 9.24 (December) corroborating with peak breeding of female in winter and spent phases in summer months. The maturity stages in females were distinguished into immature, early maturing, late maturing, mature and spent. The fecundity varied from 0.327 million to 3.41 millions in the size range of 8.7cm to11.4.cm carapace length and 160gm to 375gms of body weight. A linear relationship was found between the logarithmic relationship of fecundity and carapace length, carapace width, total weight and ovary weight. The fecundity against ovary weight was found to be a better index than total weight, carapace length and width.
