In the Mekong River Delta (Vietnam), tra catfish farms (Pangasianodon hypophthalmus, Sauvage) are threatened with predicted sea level rise and low flow of the Mekong river during the dry season, responsible for intrusion of saline water from the China Sea and the Thailand Gulf. The study in the effect on intermediate and high salinity is looked at changes in the principal osmoregulatory organs (gill NaK-ATPase activity and plasma osmolality). As stress could induce immunodepression, immunocompetence is evaluated via several stress (plasma glucose and cortisol level) and immune indicators (Fulton?s condition factor, blood cellular component, lysozyme assay, alternative complement pathway, total immunoglobulins, splenosomatic index, intracellular superoxide production, Heat Shock Protein production) as well as the capacity of tra catfish to cope with a current bacterial infection, Edwardsiella ictulari, responsible for enteric septicemia in catfish farms. A survey in six tra catfish farms was carried out during the dry season 2013 in the Lower and Upper Mekong River Delta. This survey allowed to take stock of the current state of the principal osmoregulatory and immune organs in tra catfish farms in relation to their geographical location and proximity to the River Mekong Estuary. The survey was completed with a laboratory experiment in which tra catfish were faced to two increased salinity profiles up to 10 ppt and 20 ppt during a 20- day experiment. On day 20, fish were challenged with Edwardsiella ictaluri and mortalities were recorded daily during 14 days. Blood and organs were taken on day 0, day 10 and day 20 and day 3 after challenge, the analysis of stress indicators, osmoregulatory parameters and immune factors were performed.