Abstract: Background and Objective: Formulation of probiotic mixtures for marine shrimps are still not perfect, the concept of probiotics is totally unfamiliar for freshwater-cultured prawns. This study was an attempt to evaluate the nutritional efficacy of two putative probiotic strains Bacillus subtilis RCMB21 and Pseudomonas fluorescens RCMB39. Materials and Methods: Bacillus subtilis RCMB21 and Pseudomonas fluorescens RCMB39 were separately in a commercial formulated feed for shrimps. (1) Coating the feed, with agar as the binder and (2) Fermentation of the feed with bacteria. Feeding experiments were conducted for 60 days on Macrobrachium malcolmsonii (M. malcolmsonii) with probiotic incorporated diet and growth and nutritional quality improvement of the prawn were assessed. Data were analyzed using two-way analysis of variance (ANOVA) using SPSS. Results: Bacillus subtilis coated diet, the increased weight was 3.5 times over the initial and 2.7 times for Pseudomonas fluorescens coated feed at the end of 60 days. Similar results were obtained for protein, carbohydrate and lipid. Electrophoresis of muscle showed dense intense polypeptide fractions of 200, 70, 40 and 20 kD. Fatty acid profile of prawns showed 47.43% saturated fatty acids, 13.71% monoenes and 38.8% of polyunsaturated fatty acids. Conclusion: Based on growth and biochemical studies, it could be assumed that bacteria coated diets performed better over diets fermented with bacteria. Between the bacteria incorporated, Bacillus subtilis had more beneficial properties.