Effects of ZnO nanoparticles and Zn ions on gill histopathology of rainbow trout (Oncorhynchusmykiss)

The purpose of this study was to the effect of ZnO NPs and Zn ions on gill histopathology of rainbow trout (Oncorhynchusmykiss). In this study, 60 rainbow trout were used. Moreover, two non-lethal concentrations of ZnO NPs and Zn ions included 0.5 mg L-1 and 0.05 µg L-1 with the control group (no chemicals) were used. After 14 days of exposure to these materials, gill tissue samples were taken. In order to study classical histological, samples prepared by hematoxylin - eosin staining and by optical microscopy slides were photographed. The most important damages caused on the gill tissue are including curvature secondary lamella, hypertrophy, increased mucus secretion, aneurism, hyperplasia, and finally necrosis. The levels of damages on exposed to Zn NPs were higher than Zn ions; and severity of tissue damage in 0.5 mg L-1 was higher than 0.05 µg g-1. According to results, we can say that NPs can impact and damage the fish's gill tissue, so it is necessary to pay attention when using these NPs done more and release it into the environment be avoided.