Pathology of copper nanoparticles on liver histoarchitecture and haemato-biochemical parameters of rainbow trout (Oncorhynchus mykiss) fingerlings before and after a recovery period

Nowadays due to rapid development and wide applications of nanosized matters, the possibility of their discharge into water bodies and their subsequent toxicity to aquatics are also increased. Total of 135 fingerling rainbow trout with an average weight of 30g were randomly allocated to three treatments in a two-stage completely randomized design experiment. During first 21 days, fish were exposed to three concentrations of the nanoparticles, namely, 0, 25 and 50 ppb. The final post nanoparticle exposure stage was also lasted for 21 days to scrutinize the ability of fish to recover from damage of first stage. Some hematologic, hepatic and biochemical indices of rainbow trout were evaluated at the end of each stage (days 21 and 42). Light microscopic analyses demonstrated cytoplasmic and vacuolated degeneration in hepatocytes enclosed to sinusoids, which were changed to severe hepatic necrosis and inflammatory exudate accumulation. Results from the first stage indicated that GGT was significantly (P