Objective- This study aims to determine the efficacy of propofol in grass carp anesthesia and to examine the impact of the drug on electrocardiogram, pH and blood gases in this fish species. Design- Experimental study. Animals- 120 apparently healthy grass carps, weighting between 1-2 kg. Procedure- Fishes were sorted randomly into 12 groups of 10 fish each. Five groups were anesthetized by bath method with the concentrations of 2, 4, 6, 8 and 10 mg/l and the other 5 groups by injection method with doses 2, 4, 6, 8 and 10 mg/kg, IV. Two groups were considered as control. At time of anesthesia and recovery, arterial blood samples from dorsal aorta of fish were taken and electrocardiogram (ECG) was recorded. Results and Conclusion- In bath method groups, the arterial blood oxygen in 2 mg/l group was significantly higher than the control group. In 10 mg/l group it was significantly lower than the control. CO2 and pH showed no significant difference between groups and controls. In injection groups, the arterial blood oxygen in 2 mg/kg, IV and 10 mg/kg, IV, was significantly lower than the control group. CO2 in 6 and 8 mg/kg, IV group was significantly higher than the control but there was not any significant difference between CO2 and pH in other experimental groups and control. Moreover, it was found that the average of heart rate in all groups of propofol anesthesia was significantly higher than the control groups (p<0.05) and in all groups in ECG, r to r distance (rr) has decreased. However, in ECG, no difference in the heart rate, rr, pr, qrs, qt distances was observed among all groups of recovery and the control. Clinical Relevance- Results of this study can be used in anesthesia of fish for decreasing stress and movement at the time of surgery, diagnosis and in fish artificial fertilization procedure.