Viscosity (4.3 mm2/s) and COM (2.5 °C) were minimized when pure fish oil was used as raw material, whereas IP maximum (22.0 h) was found for palm oil biodiesel. Multi-objective optimization evidenced that although the use of the pure oils as feedstock presented more advantages to biodiesel properties, the waste fish oil (42.1 wt.%) and waste frying oil (57.9 wt.%) mix is beneficial, if the aim is IP (20%) and COM (80%) improvement