The tilapia was fermented with two combinations of three lactic acid bacteria (LAB) strains: Pediococcus (Ped.) pentosaceus MFL, Ped. pentosaceus MFS and Lactobacillus (Lb.) plantarum BCRC12250, and non-starter as a control group. After 24 hr fermentation, pH value of LAB added groups rapidly declined to under 4.6 and the cell count can get up to 8.30-8.85 log CFU/g, which became the predominant strains, and other microorganisms were inhibited. In antioxidative experiment, compare with the scavenge DPPH free radical ability of blank and control group was shown 40.12% and 75.83%, respectively, LAB added groups have a better activity (94.93-95.42%). However the chelating Fe2+ efficiency of LAB added groups were inferior to blank (98.86%) and control group (96.30%), but they still had 68.17-90.69% ability. In the inhibition of hemoglobin-induced linoleic acid oxidation assay, MFL+MFS group exhibited 81.44% inducing activity and followed with the MFL+MFS+12250 group (71.44%), control group (68.33%) and blank (41.73%). A same tendency in the reducing power, LAB added groups were A700 nm = 0.85. Overall, LAB added groups displayed a higher antioxidative ability.