Metal oxide nanoparticles (NPs) have different industrial applications so it is unavoidable that NPs products could find their way into aquatic habitats. Therefore, toxic NPs must be treated sufficiently to reach the standard values before their discharge into the aquatic ecosystems. Our study aimed to investigate the adsorptive capacity of rice husk to iron and aluminum oxides from water and reducing their potential toxic effects. Fish were classified into eight groups for 7 days: Fe2O3 NPs (10 mg/l)-exposed group; Al2O3 NPs (10 mg/l)-exposed group; combined group (same concentrations of Fe2O3 and Al2O3NPs), and control group (dechlorinated water). The other four groups were the same as the above groups but with 50 mg/l rice husk in each group. Compared with control groups, our results showed a significant (p < 0.05) increase in plasma total proteins, globulin, glucose, liver enzymes, and kidney function biomarkers (creatinine and uric acid). While the recorded albumin and total lipids were significantly decreased. The oxidative biomarkers in liver and gill tissues of NPs-exposed fish showed significant (p < 0.05) reduction in glutathione-reduced content and elevation in thiobarbituric acid reactive substances, glutathione peroxidase, catalase, and superoxide dismutase. Based on our results, Fe2O3 NPs were more toxic than Al2O3 NPs. The combined doses of both NPs showed more or less toxicity compared to single doses. Therefore, this point needs more studies to show the mode of interaction. Finally, rice husk was a good adsorber to both NPs as it could improve the biochemical and antioxidant status of the studied fish.
Keywords: Aluminum oxide NPs; Iron oxide NPs; Oreochromis niloticus; Rice husk.