The goal of this study is to assess the acute and sublethal potential hazards on tilapia fish (Oreochromis niloticus) exposed to two different commercial formulations of abamectin (ABM, 5%): emulsifiable concentration (EC) and microemulsions (ME). The median lethal concentration (LC₅₀ - 96 h) to each formulation was determined, as well as the adverse effects of sublethal concentrations (½ LC₅₀) on physiological and oxidative stress biomarkers after 96hs of exposure. The LC₅₀ (96 h) values for EC and ME were 10 and 16.6 µg/L, respectively. Furthermore, in both EC and ME, the findings of physiological and oxidative stress aspects revealed significant markedly increases in serum total protein, albumin, globulin, and urea, as well as a significant decline in aminotransferases activity (ALT and AST), and creatinine levels (Cre). Moreover, superoxide dismutase (SOD), malondialdehyde (MDA), catalase (CAT), and glutathione peroxidase (GPx) were greatly increased, whereas glutathione-S-transferase (GST) and glutathione (GSH) were significantly reduced in the liver and brain.