Histopathological study of gill and liver of Epaulet grouper (Epinephelus stoliczkae) under the chromium effect

Histopathological changes as biomarkers in risk assessment of fish health are used in both laboratory and field environments. In this study, the histopathological lesions induced by sub-lethal concentrations of chromium was investigated in gill and liver of Epinephelus stoliczkae under laboratory conditions. For this purpose 200 number of Epinephelus stoliczkae with an average weight of 389.5±92.4g and the average total length of 29.6±2.2cm were exposed to three concentrations of 3.6, 7.31 and 14.6ppm of chromium for 21 days in the laboratory fixed conditions, and samples of gill and liver tissues were extracted in during 0.5, 1, 7, 14 and 21 days after start the experiment. Results of histopathological studies by light microscopy in the gill tissue were clubbing, hyperplasia, hyperemia and epithelial lifting of the lamellae, and in the liver tissue were necrosis, vacuolation, Irregular of hepatocytes, melanomacrophage centers and dilatation of liver sinusoids. Results of histopathological studies showed special relationship between chromium concentration and severity of lesion. The most severe lesion was observed at higher concentrations of chromium and longer duration of exposure, in the fish tissues.