We studied some aspects of biology of the Altantic mudskipper, Periophthalmus barbarus, in two estuarine swamps of Qua Iboe River, Nigeria, between January and December 2004. Sexual dimorphism revealed that males from mangrove creek swamp were longer than their nipa creek swamp counterparts whereas in the latter creek swamp females grew longer than the females of the former creek; there as no difference in weight between the creeks. Sexes were differentiated on the basis of the gentilia. There were more females than males in both the mangrove and nipa creeks. The overall sex ratio between the two creeks satisfied the ‘null hypotheses. Mudskippers from the mangrove and nipa creeks ingested 31 and 32 food objects respectively; although similarity occurred in the rank-order of the %MFON of the food objects [rS = 0.564, p