Abstract: This study examined the ecotoxicological evaluation of commercial fish pond in Ogbogoro, Port Harcourt, and Rivers State Nigeria using the histological assessment of Clarias gariepenus, using African Aquaculture Centre (ARAC) as a reference site. The sampling involved harvesting of twenty table sized fish from Ogbogoro commercial fish pond and ten table-sized of the same species from ARAC. The histological assessment involved the determination of the qualitative and semi-quantitative analysis of the gills of the harvested fishes. Histological alterations observed were based on circulatory disturbances (CD) which includes hyperemia, haemorrhage, vacuolation. Regressive change (RC) which includes necrosis and progressive change (PC). Results showed that tissue samples of gills showed an almost equal prevalence in histological alterations in OGB as compared to ARAC, where gill was 16.67% against 16.68%. The Histological Alteration Index, that is, mean fish Index (FI) for OGB is 14.7, making it slightly greater than ARAC, which is 14.6. It was concluded therefore that the OGB fish pond was moderately polluted.