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Abstract: From April 1992 and March 1993, morphometric characteristics and reproductive maturation were studied in Periophthalmus barbarus from subsistence catches in the mangrove swamps of Imo estuary. Morphometric equations for males and females at different stages of ovarian maturation are presented. Generally males were significantly heavier in weight than females, but the latter were heavier than the former of the same body length. Females with developing and mature ovaries were generally heavier than immature females of the same length. Analyses of the gonadosomatic index and percentage of mature males and females indicate all year-round breeding such that: February-May was spawning, June-October postspawning and November to January recovery period. Fecundity varied between 900 and 23933 eggs per spawn and increased with fish size. [ABSTRACT FROM AUTHOR]

Abstract: Between April 1992 and March 1993, intersexual plasticity in aspects of the biology of the mudskipper, Periophthalmus barbarus was studied. Sex was differentiated on the basis of the genital papillae, it was broader in females than males. Sexually active females were slightly heavier than similarly-sized males. Sex ratio was strongly female-biased. Length-weight relationship of the sexes was isometric. There was no significant difference in the feeding intensity of both sexes; uniformity was also apparent in diet breadth. There was no named sex-based difference in hepatosometic index but condition index was higher in males than females. The uniformity in intersexual plasticity of P. barbarus is consequent upon homogeneity of the mangrove ecosystem, which can only be altered anthropogenically. [ABSTRACT FROM AUTHOR]

Aspects of the trophic attributes of the mudskipper, Periophthalmus barbarus occurring in the mangrove swamps of Imo River Estuary, Nigeria, were investigated during a 12-month period (April, 1992-March, 1993). Feeding intensity increased with size, it was higher in the dry season(November-April) than in the wet season(May-October), monthly changes in the indices of feeding intensity were significantly correlated. Major food objects comprised detritus and benthic algae; crustaceans, insects, macrophyte matter and sand grains were minor food objects while fish, molluscs, Chilopoda, nematodes and fungi were unconsciously devoured objects. Diet varied seasonally; algae and sesarmid crabs were generally more in the dry season than during the rains whereas FPOM and fish increased in the wet over dry season. The mudskipper display a high degree of euryphagy and can be considered as a generalist and an omnivore. The lower trophic status of P. barbarus qualifies it as a good aquaculture candidate. Food richness was higher in big-sized class(BSC) than small-sized class(SSC). Size-based and seasonal variations were not apparent in food richness. Diet breadth was higher in the BSC than the SSC, there was dry season increase in diet breadth.