Tilapia fanning applied technology biofloc is created optimal conditions for development heterotrophic microorganisms dominate, heterotrophic microorganisms use organic carbon as food and absorption of inorganic nitrogen to protein in the biomass and formation of biofloc. This farming technology is the goal of economic efficiency, environmental pollution reduction as well as product quality. Therefore, the assessment of microbiological indicators of food safety on tilapia by the farming biofloc technology is done to determine the level of some microorganisms infection affecting food safety which assesses the product safety compared with the current Vietnamese regulations and the world's. Microbial indicato.,IS are quantified by the MPN method (Most probable Number technique) on lauryl Triptose broth, according to the TCVN 4882: 2007, TCVN 6846: 2007 and quantitative methods (directly counting the number of bacteria on the feeding environment) of S. D. Millar and G. N. Frerchs (Stirling, 1984, 1993).