Performance of food safety management system (FSMS) by Self diagnostic instrument (DI) and Microbial assessment scheme (MAS) are still new approaches in Vietnamese Pangasiusprocessing industries. Performance variability of food safety management systems (FSMS) in practice during processing steps makes microbial quality and safety of Pangasiusproducts very challenging. Therefore, 117 samples of fish, water and environment were collected throughout processing to assess the effective operation of the FSMS in practice. The dynamics and variations in the microbial quality and safety were observed. The microbial count of the final products ranged 6.8-7.7 log CFU/g of total mesophilic count, was observed on processed fish; 15/36 Listeria monocytogenesand 1/36 Salmonella spp. with a similar trend in food contact surfaces, hands of operators and water. More attention should be focused on this company because the current FSMS is not performing effectively by means of SelfDiagnostic Instrument (DI) and Microbial Assessment Scheme (MAS) tools. These assessment tools are necessary to implement routinely to validate the FSMS in place