Abstract: The aim of this research was to evaluate the effect of detergent (linear alkylbenzene sulphonate) on selected blood plasma metabolites of African mudfish (Clarias gariepinus) juveniles and adults. The effect was assessed by comparing blood plasma metabolites profile in the two live stages of a control group (0.00 mg L^–1) and that exposed to varied concentration of detergent (10.00, 20.00, 30.00, 40.00 and 50.00 mg L^–1). Compared with control group, albumin was 10.92, 8.48, 9.10% higher than control at 10.00, 20.00 and 30.00 mg L^–1 and 12.08, 14.97% lower at 40.00 and 50.00 mg L^–1 for juveniles while for adult fish it was significantly (p>0.05) higher than control at all the concentration levels. Total protein was 11.70, 15.20, 15.79, 22.22 and 28.07% higher than control at all levels and significantly not found in the adult. Creatinine was respectively 45.29, 125.96, 55.25 and 50.36% higher than control at 10.00, 20.00, 30.00 and 50.00 and 2.75% less than control at 40.00 mg L^–1 while in adult fish it was observed that at 10.00-50.00 mg L^–1, creatinine was respectively 72.73, 157.27, 239.09 and 280.00% higher than control. Interestingly, total bilirubin in juvenile fish was 69.50, 76.12, 86.91, 76.12 and 92.09% less than control while in adult fish, it was 15.58, 32.92, 63.03, 114.95 and 136.24% higher than control at 10.00-50.00 mg L^–1. The exposed group for juvenile and adult fish showed a significantly higher (p<0.05) concentration of urea when compared with that of the control group.