Toxicological effect of Al2O3 nanoparticles on histoarchitecture of the freshwater fish Oreochromis mossambicus

•Toxicological effect of Al2O3 nanoparticles were studied using the freshwater fish Oreochromis mossambicus.•Sub lethal concentrations (120, 150 and 180 ppm) of Al2O3 NPs were exposed to the fishes for a period of 96 h.•Histoarchitecture of selected organs (brain, gill, intestine, kidney and muscle) in the control and treated fishes were observed.•Histological anomalies were initiated in the fishes exposed to the lower concentrations of NPs.•The severity of lesions were more evident in fishes exposed to the highest concentration of nanoparticles. In the present study, freshwater fish Oreochromis mossambicus were exposed to sub lethal concentrations (120, 150 and 180 ppm) of Aluminium oxide nanoparticles (Al2O3 NPs) for 96 h. Histological abnormalities were not observed in the organs of control fishes whereas severe damages and extensive architectural loss was found in the brain, gill, intestine, kidney and muscle tissues of treated fishes with more pronounced effects in 180 ppm. The results showed that the acute exposure to Al2O3NPs altered the histoarchitecture in various fish tissues.