Abstract: Clarias gariepinus juveniles were exposed to sub-lethal malachite green concentration of 0.15 mg L-1 at different exposure period of 6, 24, 48, 72 and 96 h to assess the metabolic response of fish to malachite green. Biochemical parameters of the fish revealed that glucose, cholesterol, triglycerides, sodium (Na+), potassium (K+) and urea showed significant differences (p< 0.05) between the fish exposed to malachite green and the control fish. After 6 h of exposure, Na+, K+, glucose and creatinine increased significantly (p< 0.05). There was a slight increase in uric acid content at 6, 24, 72 and 96 h, respectively but was not significantly different from the control. The observed metabolic response of Clarias gariepinus juveniles to malachite green suggest that fish encountered toxic stress and metabolic crisis when exposed to sub-lethal dose of malachite green. It is therefore recommended that treatment of C. gariepinus juveniles with 0.15 mg-L sub-lethal dose of malachite green should not exceed 24 h.