Linear alkyl benzene is a toxicant that can adversely affect the health of a fish. The study was conducted to ascertain the toxicity effect of the detergent on haematological and serum biochemical indices in clarias angularis juveniles of fairly uniform sizes. Juveniles of C. angularis were exposed to sub-lethal concentrations (0.0mg/l, 0.45, 0.60, 0.75, 0.95 & 1.05mg/L) of the detergent derived from the 96hour lethal concentrations for eight weeks. The result of the study revealed that significant changes and dose dependent decreases in red blood cell (RBC), packed cell volume (PCV) and haemaglobin (Hb) values were observed in detergent exposed fish compared to the control. Progressive increases in white blood cell count (WBC) were found in detergent exposed fish compared to the control. Significant increases in biochemical parameters (glucose and protein were observed in detergent exposed fish groups compared to the control. However, cholesterol levels decreased significantly except for the highest contaminant concentration and duration of exposure. Linear alkyl benzene detergent incorporated into culture medium to juveniles of C.angularis was seen to have disrupted the haematological and biochemical profile of the fish.