The effects of a probiotic Lactobacillus plantarum CR1T5, at various concentrations(0, 10⁶, 10⁷, 10⁸ and 10⁹cfu g^-1) in dietary supplements for Black Eared Catfish (Pangasius larnaudii) were investigated. Fish were randomly allocated into 5 treatments with 3 replications and reared for 60 days. The growth performance, non-specific immunity and disease resistance were determined at 15, 30, 45 and 60 days. The results revealed that at day 15 the fish received probiotic dietary supplements at 10⁷, 10⁸ and 10⁹ cfu g^-1 had significantly higher Specific growth rate (SGR) and lower feed conversion ratio (FCR) than the fish received control diet. On the other hand, fish fed 10⁶cfu g^-1 dietary supplement had significantly higher SGR and lower FCR at day 45. For immune parameters, the respiratory burst activity was significantly increased after 30 days. Probiotic diets at 10⁸ and 10⁹cfu g^-1 significantly improved complement activity after 15 days and significantly enhanced lysozyme activity after 45 days of feeding. All fish received probiotic dietary supplement displayed a significantly increased survival rate post-challenge with A. hydrophila. This study found that the optimum probiotic dietary supplement at 10⁸ cfu g^-1 had significantly improved growth performance, immune stimulation and disease resistance in P.  larnaudii.