Do Multispecies Probiotics Modulate Microbiota in Finfish Polyculture System?

The present research aimed to find out role of multispecies probiotics on water and gut microbiota modulation, water quality parameters, growth rate and total production of Indian major carp species in a polyculture system. Two treatments (T1 and T2) and a control (C) with three replications were stocked with Labeo rohita, Catla catla, and Cirrihinus mrigala at a ratio of 2:1:1.06 for this purpose in FMRT discipline pond complex of Khulna University in June 2022. The results showed that the mean hardness, ammonia, nitrate and nitrite were significantly improved by water probiotics compared to control. The water and gut bacterial analysis disclosed that total heterotropic bacterial loads were significantly higher in control than water and feed probiotics respectively. Additionally, results also depicted that feed and water probiotics significantly reduced Vibrio spp. and eliminated Pseudomonas spp. though no difference between two types of probiotics. However, water and feed probiotics could not able to lessen total load of Bacillus cereus in water. Average load of Nitrosomonas spp. and Nitrobacter spp. in water sample were significantly (p<0.05) higher in T1 and T2 than C. Moreover it also explicitized that feed probiotics could able to significantly improve the mean relative weight gain (p=0.001) and specific growth rate (p=0.001) of Indian major carp species as well as mean total production (p=<0.001) at 5% level of significance.