Biofloc technology (BFT) is nowadays considered as eco-friendly approach being used for fish and shellfish production. The present investigation aimed at comparing water quality, as well as immune responses, nutritional condition and production of Ompok pabda between the traditional culture system with stocking density of 17 (TS1), 22 (TS2) and BFT system (C: N ratio of 20:1; molasses as carbon source) with 17 (BFTS1), 22 (BFTS2), 27 (BFTS3) fish of 0.30 ± 0.001 g/m2; the fishes were reared with feeding a commercial diet at 10 − 3% of their body weight for 90 days in tanks. There was significant (p < 0.05) variation in water quality parameters including dissolved oxygen, pH, total ammonia nitrogen (TAN) between the traditional and BFT tanks. The fishes of the BFTS1 had the highest specific growth rate (SGR, 4.11 ± 0.17%/day) and survival (98.33 ± 2.89%) while the TS2 had the lowest SGR (3.51 ± 0.05) and survival (86.67 ± 5.03%). The protein, lipid, essential amino acids, monounsaturated fatty acid and polyunsaturated fatty acid contents were found higher in the BFT-reared fishes compared to the TS-reared fishes. The fishes of the BFT system had also higher red blood cell (3.28x106/mm3), hematocrit (34.5%), and neutrophil counts (27.30%) than had the TS-reared fishes. Regarding profitability, the BFTS2 provided the highest benefit-cost ratio (BCR; 1.22 ± 0.04) whereas the TS1 system had the lowest BCR (0.99 ± 0.04). Altogether, the obtained results points out that the stocking density modulated the rearing environment, and thus, production of O. pabda traditional and BFT systems; considering FCR and BCR values, the stocking density of 22 fish/m2 can be feasible to bring about good economic return of a O. pabda biofloc system.