Comparative toxicity of copper oxide bulk and nano particles in Nile Tilapia; Oreochromis niloticus: Biochemical and oxidative stress

Nile Tilapia; Oreochromis niloticus are commonly used in the assessment of aquatic environment quality and also considered as useful bio-indicators during environmental pollution monitoring. The LC50/96 h of copper oxide (bulk & nano) particles [CuO (BPs & NPs)] were 2205 & 150 mg/l, respectively. Two tested concentrations of CuO (BPs & NPs) were selected: the first concentration was equivalent to (1/10) (220.5 & 15 mg/l), and the second was equivalent to (1/20) (110.25 & 7.5 mg/l) LC50/96 h·CuO (BPs & NPs), respectively. While serum glucose, liver function tests (AST, ALT and ALP) and kidney function tests (creatinine and uric acid) showed a significant increase, serum total proteins, albumin, globulin and total lipids showed a significant decrease. Both liver and gill tissues of the studied fish showed a reduction in GSH content and an elevation in MDA and GPx activities. The present study also showed an elevation in liver CAT & SOD activities when exposed to both concentrations of CuO BPs and in the case of gills when exposed to both concentrations of CuO (BPs & NPs), although activity of these enzymes showed an inhibition in the liver when exposed to both concentrations of CuO NPs. The present study investigated whether CuO NPs are more toxic than CuO BPs.