Lactic acid bacteria (LAB) were isolated from traditional Thai fermented fish, Plasom at various fermentation periods. It was found that 138 isolates exhibited a clear zone and growth on MRS agar supplemented with CaCO3; however, only 133 isolates were identified as LAB. Only 14 strains showed excellent inhibition zone diameters on agar when Salmonella sp. was used as an indicator for preliminary detection of antagonistic activity. Staphylococcus aureus was used for secondary screening for antago