Abstract: Fisheries of Erelu reservoir, South Western Nigeria was assessed using fleet of gillnets of varied mesh sizes with the intent of generating necessary data that could support sustainable use and management of the resources to enhance the socio-economic status of the riparian communities. The reservoir was stratified into upper, middle and lower zones covering an average of 1000 m each and gillnets was deployed to the shores and open water region in each zones monthly for 21 months covering 2 wet and 2 dry seasons. Fish caught were identified to lowest taxonomic level and morphometric parameters taken following standard procedures. A total of 6,927 samples belonging to 16 species and 8 families were encountered throughout the study period. Seasonally, more fish samples were recorded during the dry season (57.95%) than wet seasons. When catches were compared spatially, lower zone recorded 38.89% followed by the upper zone with 34.29% and the middle zone 26.82%. However, highest catches were recorded at the shore (57.82%). Three families: Cichlidae, Cyprinidae and Clariidae constituted 72% of the total catches and were dominated by O. niloticus, R. senegalensis, C. nigrodigitatus, S. melanotheron, S. mystus and T. marie. The forage-carnivore ratios of 1.9:1 and 1.6:1 by number and weight, respectively, recorded suggests an incongruous ecological balance. The potential fish yield was estimated as 136.55 kg ha–1 and catch per unit effort of 8.8 kg per fisherman per day was recorded. Regular monitoring of the fish composition and stocking of more forager species is recommended to balance the community structure.