The study was carried out to elaborate the reproductive aspects, including size at sexual maturity, reproductive season, reproductive potential, and egg size of Glossogobius giuris from Manchar lake, Sindh, Pakistan for the first time. Manchar lake is polluted lake, it is situated in district Jamshoro. The survey was conducted from February to December 2010. In total 335 specimens comprising of 159 females and 176 males were brought to the laboratory. Fish specimen were measured for total length (cm) and weighed (g) on digital balance. After dissection gonads of each specimen were weighed. Gonadosomatic Index was calculated as GSI=(GW × 100)/BW; Ovaries were preserved for fecundity estimation. The total length of smallest and largest specimen observed was 9.5 cm-24.8 cm, respectively. First size at the sexual maturity of female G. giuris was observed 9.5 cm. Gonadosomatic Index of G. giuris was high from April to June. Fecundity of fish ranged between 7346.45 to 39750.45. The average fecundity of G. giuris was 24835.84 ± 10361.74. Study revealed that fecundity of G. giuris in Manchar lake is not as high as in neighboring countries. Study also revealed that the species has single and short spawning season in Manchar lake.