This study aimed to evaluate the fate of in water microcosm and rainbow trout fillet under salinity stress of 0% and 30% NaCl at refrigerator temperature (4 ± 2 ℃). Bacterial culturability was studied by standard culture and colony count method. Reverse transcription-PCR (RT-PCR) of gene was used to detect viability of non-culturable bacteria. Also, the qualitative expression of pathogenic genes () was studied using RT-PCR. The results showed that bacteria in water microcosm lost their culturability at 13 days under 0% salinity (starvation or distilled water) and at 27 days under 30% salinity; however, bacteria in rainbow trout fillet remained culturable under 0% and 30% NaCl. RT-PCR of gene was positive for all treatments during the period of this study, indicating the entering of into the viable but non-culturable state in water microcosm under 0% and 30% NaCl. Also, viable but non-culturable retained the expression of and genes. So, it could be concluded that in viable but non-culturable state can cause serious health problems and further investigation is necessary to elucidate the effects of other processing and storage conditions (light, dark, smoking, etc.) on behavior of in smoked and salted fish.