Evaluation of probiotic susceptibility of virulent Aeromonas sp. by a study on gut histology of Cyprinus carpio

Bacterial diseases are the chief constraint in the aquculture industry. Among them Aeromonads causes majority of production loss in fresh water ornamental fish farming. Trend of application of probiotics in any aquaculture farm is being increasing to reduce the environmental degradation caused by chemical treatment methods. In this study, Aeromonas veronii was isolated from diseased koi carp and its virulency was re-confirmed with mortality rate of 73.33 % in koi carp. Susceptibility of A. veronii to commercial probiotic mixture of Bacillus species was proved by in vitro assay where zone of inhibition of 22.67 +/- 0.6 mm diameter was observed at 108 CFU mL-1. Bacillus probiotic mixture at 108 CFU g-1 maintained the gut morphology with good goblet cell count against A. veronii infection in koi carp. Thus, severe production loss due to A. veronii in ornamental fish farms can be controlled by probiotic dietary supplementation.

Automated summary

Bacterial diseases, particularly Aeromonads, pose a significant threat to fresh water ornamental fish farming. The trend of using probiotics in aquaculture is on the rise to combat environmental degradation caused by chemical treatments. In this study, a commercial probiotic mixture of Bacillus species demonstrated efficacy in controlling Aeromonas veronii infections in koi carp, thus reducing production losses.