The research aimed isolation of lactic acid bacteria capable of pathogen inhibitory activity from gastrointestinal tract of sea bass (Lates calcarifer). Collection of 121 yellow colonies on the selective medium, MRS agar added with bromocresol purple and CaCo3 88 isolates are gram-positive, non- sporulation and catalase negative. Lactic acid bacteria are rods 4 isolates, medium rod 7 isolates, cocci 77 isolates and Homofermentative. The research 48 isolates lactic acid bacteria can inhibits Aeromonas hydrophila and Streptococcus sp. The best Isolates 1/84 (LAB 33) can inhibits Aeromonas hydrophila with a diameter about 13.17±0.29 cm. and Isolates 1/69 (LAB25) can inhibits Streptococcus sp. with a diameter about 21.00 ±1.00 cm. Therefore the bacteriocin activity of isolates 1/69 (LAB25) was calculated as 800 AU/ml.