Sarosate induced changes on some blood cells and metabolites activity of Heterobranchus bidorsalis (hybrid), a common Niger Delta wetland fish were assessed. Adult fish (mean length, 15.07±0.29cm) were acclimatized to laboratory conditions for nine days and then exposed to varying sublethal concentration of sarosate (1.00, 2.00 and 3.00gl-1) in a semi static bioassay for 32 days. All the parameters were determined in the plasma. Some blood cells (red blood cells (RBC), white blood cells (WBC), platelets) values were significant (p < 0.05) almost in a dose dependent pattern. RBC values increased as the concentration of sarosate increases, TWBC only showed a significant value at the last concentration, compared to control. Platelets values observed were not concentration-dependent pattern. Bilirubin values at the last concentration were statistically significant. Albumin values fluctuate within the experimental group. A slightly retrogressive value was observed in platelets, akin to haemoglobin at 1.00 and 2.00gl-1. It is concluded that sarosate at high concentration could be toxic to Heterobranchus bidorsalis. The use of sarosate in the aquatic environment should be done with caution. Additionally, Blood cells and metabolites parameters used in this research may serve as useful biomarkers of sublethal effect of sarosate on Heterobranchus bidorsalis.