Abstract: Study was carried out on mudskipper, Periophthalmus papilio in Lagos lagoon, Nigeria to provide information on length-weight relationship and fecundity estimates. Periophthalmus papilio is of an amphibious fish and a member of the family periophthalmidae. A total of 2,167 individual of the specie were caught from the lagoon using non return valve traps. Biometric data such as Total Length (TL) and Body Weight (BW) measurements were recorded in the laboratory. The specimens ranged from 30.0 to 190.0 mmTL and weighed between 0.5 and 65.3 g BW. The mean TL measurements were 76.0566±1.415, 115.953±0.999 and 111.361±0.812 mm and weighing 5.908±0.393, 18.808±0.507 and 16.769±0.367 g for unsex, males and females, respectively. The length weight relationships were: Log W = -4.1053+2.5522 Log TL (n = 185, r = 0.9385) for unsex; Log W = -4.6804+2.8606 Log TL (n = 532, r = 0.9684) for males and Log W = -4.7916+2.915 Log TL (n = 746, r = 0.9784) for females. The growth exponential b values were allometry in this species. The fecundity estimates of the species varied between 508 and 15,700 ripe eggs for fish with size from 91-180 mmTL and 9.1-65.3 gBW. The mean fecundity estimate was 3,482±102 eggs for average fish of 116 mmTL. Positive correlation was exhibited by the fish between its fecundity and body weight (r = 0.4041) and total length (r = 0.3810). The Gonadosomatic Index (GSI) values of the fish varied between 0.01 and 0.48% in males and 0.11-8.40% in females. Higher GSI values indicate a better well being for the fish.