Biochemical biomarkers in Nile tilapia (Oreochromis niloticus) after short-term exposure to diesel oil, pure biodiesel and biodiesel blends

► First evaluation of biodiesel effects in endpoint biomarkers in an aquatic organism. ► Oxidative stress in Nile tilapia exposed to diesel, pure biodiesel, B5 and B20. ► Pure biodiesel also caused oxidative stress in tilapias. ► Diesel and biodiesel alter levels of MDA, 1-OH-pyrene and enzyme activity. ► B20 had fewer adverse effects than diesel, and B5 for Nile tilapia.