Bioaccumulation of some heavy metals in water and tissues of naturally infected Oreochromis niloticus from two polluted sites in Egypt, with reference to related oxidative stress

The present research was planned to assess the harmful effects of heavy metals as well antioxidant alterations Oreochromis niloticus collected from two polluted fish farms located in Abbassa and Manzala (areas A B, respectively) Egypt. They were compared with reference site central laboratory for aquaculture researchers during summer season, 2020. total number 75 all sites subjected clinical, postmortem, bacteriological examination. Water parameters, (arsenic, manganese, nickel) water, serum, tissues (muscle, gills, liver), evaluated. In addition, enzymes (SOD CAT) (MDA) assessed serum O. niloticus. Bacterial isolates, Aeromonas hydrophila, identified at both localities, recorded mortality rate about 30% 5% areas respectively. levels As water samples higher than permissible limits. showed a significant decrease concentrations Ni areas. mean found gills muscles  Moreover, CAT, combined increase SOD activities observed area A.