In this study, the optimum conditions (methanol/oil mole ratio, temperature, and so on) for producing biodiesel with fish oil (menhaden oil) were established. The length of the carbon chain of fish oil is frequently greater than that of general vegetable oils. Therefore, the use of fish-oil based biodiesel with larger cetane number may improve diesel engine performance and result in a reduction of pollutant emissions. The optimum conditions of the manufacture of biodiesel with menhaden oil were reaction time of 120 min, reaction temperature of 55 ℃, methanol/fish oil molar ratio of 12, and alkaline catalyst content of 2.0 wt%. In the performance evaluation of the biodiesel produced, the acid value (0.20 mg KOH/g), kinematic viscosity (4.60 cSt at 40 ℃), and higher heating value (42.1 MJ/k) biodiesel quality standards were suitable.