RESUMO
Pharmaceuticals are used extensively in human and veterinary medicine to eradicate or prevent diseases. The residues of these drugs have been detected in aquatic ecosystem; nevertheless, their toxicological effects on Clarias gariepinus have not been critically investigated. In this study, the toxic effects of diclofenac (DCF), a non-steroid anti-inflammatory drug, were studied in C. gariepinus by acute and chronic static renewable bioassay. The 96 h LC50 of DCF to C. gariepinus was 25.12 mg/L. Exposure to acute toxicity resulted in abnormal behavior and mortality of some fish. Compared with the control, chronic exposure of the fish to concentration (1.57, 3.14 and 6.28 mg/L) showed significantly higher mean corpuscular haemoglobin concentration (MCHC), mean corpuscular volume (MCV) and white blood cell (WBC), with significantly lower haemoglobin (Hb), haematocrit, red blood cell (RBC) and mean corpuscular haemoglobin (MCH) with increase in the concentration of the drug. Furthermore, the levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), lactate dehydrogenase (LDH) and glucose values significantly increased while protein levels were reduced (p < 0.05) in serum and gills throughout the 42-day exposure period. The study reports that DCF-induced enzymatic and haematological changes in the fish and recommends that these parameters be used as potential biomarkers for assessing residual pharmaceuticals available in aquatic ecosystem.
