Histopathology of rainbow trout gills after exposure to copper

Copper is a very common element in water resources. For this reason, concerns about the risks and consequences of this element in water contamination are arising. The purpose of this study was to investigate the effects of water-born CuO (Copper (II) oxide) on the rainbow trout, Oncorhynchus mykiss gill tissue to establish a suitable biomarker for copper in water resources. Samples with 18±3g body weight were exposed to CuO for a week with 0.0125, 0.037, 0.075, and 0.15 ppm of copper sulfate and a control group (without CuO). Physicochemical properties of water were 15±2ºC, pH 7-8, Caco3 270mg/l and oxygen saturation 90.9±0.2%. At the end of 7 days, 9 fish were caught randomly from each treatment and second gill from left side of fish were removed for histological study. Hyperplasia, oedema, epithelial lifting in secondary lamella and lamellar aneurysm were observed in gill tissues, showing that CuO, as a copper ion, has significant adverse effects on gill tissues of rainbow trout and gills can be a suitable biomarker for copper in water resources.