Bacterial and metal quality of tilapia (Oreochromis nilotica) aquaculture systems

Bacterial quality of four tilapia (Oreochromis nilotica) growing pond systems based on total coliforms, Aeromonas hydrophila, Yersinia enterocolitica and Campylobacter jejuni occurrence was examined. Surveys were conducted during the rainy and dry seasons. Results showed that the bacteria were present in feed, pond water and sediment. Seasonality in the incidence of the bacteria was observed, with higher numbers recorded in the dry than in the rainy season. Site‐specific sampling programmes were conducted to determine levels of metals (K+, Ca2+, Fe2+, Mg2+, Cu2+and Cr3+) in the fish environment. Higher metal levels were encountered in sediment than in the water column. The metal concentrations showed an inconsistent seasonality.