Efficacy of supplementary diet with a mixture of Bacillus spp. and Lactobacillus spp. probiotics in enhancing water quality, growth performances, serum and skin mucus parameters of Nile tilapia (Oreochromis niloticus) in two recirculating and exchange water systems

The efficacy of supplementary diet with a mixture of Bacillus spp. and Lactobacillus spp. probiotics in enhancing water quality, growth performances, serum and skin mucus parameters of Nile tilapia (Oreochromis niloticus) was investigated in four treatments: T1- water exchange system without probiotics; T2, water exchange system with probiotics; T3, zero-exchange biofloc system with probiotics; T4, zero-exchange biofloc system without probiotics, for a period of 90 days. At the end of study, the mean final weight, weight gain, specific growth rate, and feed conversion rates were found significantly (P<0.05) higher in biofloc-based treatments (T3 and T4) versus tanks with water exchange (T1 and T2). The mean values of total ammonia nitrogen (TAN) concentrations and pH were significantly lower in tanks with water exchange (T1 and T2) compared to biofloc treatments (T3 and T4), Meanwhile, probiotic application showed to significantly improve serum immune responses (ACH50 and superoxide dismutase) and skin mucus parameters (total protein, total immunoglobulins, protease activity, lysozyme activity and alkaline phosphatase activity) in both systems. In conclusion, biofloc technology and dietary probiotic administration beneficially enhanced the growth performances as well as serum and skin mucus immune responses of tilapia.