Abdulkareem, S.I.Abdulkareem, A.O2025-04-072025-04-072025-04-03https://uilspace.unilorin.edu.ng/handle/123456789/14970The indiscriminate discharge of effluents from Zinc oxide nano-particles (ZnO-NPs) industries into water bodies can cause genetic disorders in fish. The genotoxicity of ZnO NPs was investigated on Juveniles of Heterobranchus longifilis through exposure to sub lethal concentrations (6.00, 8.00, 10.00, 12.00 mg/L) of ZnO-NPs for 60 days, and fish were fed on ascorbic acid (50.00, 250.00, 500.00, 1000.00 mg AA/kg diet) for 30 days. After each experiment, the micronuclei (MN) abnormalities and deoxyribonucleic acid (DNA) quality were evaluated. The commonest abnormalities recorded are micronucleated, binucleated, multinucleated, altered, echinocyte cells, kidney-shaped and deformed nuclei. However, groups ameliorated with a 500 mg AA/kg diet recorded little or no abnormalities. A dose and time-dependent increase in MN induction and frequency occurred compared to control but decreased (p<0.05) as the concentration of AA increased. There were highest MN induction and frequencies in the liver (38.23%) than in gills (26.32%) and blood (24.61%) of ZnO-NPs-exposed fish, with the lowest MN induction and frequency in the liver (10.21%), gills (1.76%) and blood (1.61%) of 500 mg AA/kg diet-group. DNA quality reduced with increasing concentrations and exposure periods but improved in the 500 mg AA/kg diet group. This indicated that ZnO-NPs are toxic, but 500 mg AA/kg-diet was able to minimize MN induction and DNA damage in H. longifilis.