Assessing the detrimental impact of varied doses of dietary ZnO nanoparticles on Tilapia niloticus: Implications for fish health

Abstract

The investigation and monitoring of exact mechanisms of induction of deleterious effects induced by various synthetic and natural compounds including nanoparticles (NPs) are crucial to lowering the toxic effects of these compounds both on public health and the environment. For this purpose, zinc oxide nanoparticles (ZnO NPs) were synthesized using the co-precipitation technique. SEM (scanning electron microscopy) showed that the synthesized NPs had formed spherical structures, and were collected as flower-shaped bundles. The calculated average crystalline size of ZnO NPs from XRD (X-ray diffraction) was 17.6nm. A total of 150 fish (Tilapia niloticus) were reared in cemented tanks having 200L water in different groups (T0 and T1-T3). The fish in groups T1-T3 were exposed to ZnO NPs mixed in feed @ 150mg/kg, 300mg/kg, and 450mg/kg respectively for 28 days. The results revealed significantly increased morphological and nuclear ailments in erythrocytes of fish exposed with higher doses of ZnO NPs (300mg/kg and 450mg/kg) in comparison to unexposed fish. Hematological analysis showed significantly decreased red blood cell count (RBC), hemoglobin, and lymphocytes while an increased population of white blood cell count (WBC) and neutrophil at higher doses (300mg/kg and 450mg/kg). Serum biochemistry analysis indicated significantly increased concertation of cholesterol, creatinine, urea, alanine transaminase (ALT), aspartate aminotransferase (AST), and alkaline phosphatase (ALP), and decreased quantity of total proteins, globulin, and albumin in fish exposed to higher doses of ZnO NPs. The results on the oxidative and antioxidant status of exposed fish unveiled a significantly increased profile of reactive oxygen species (ROS) and thiobarbituric acid reactive substances (TBARS), a by-product of the lipid peroxidation (LPO) process and a lower quantity of different antioxidant enzymes. The results indicated that higher doses of ZnO NPs disrupt the physiological mechanisms of fish via induction of hemato-biochemical profile and induction of oxidative stress in multiple tissues.