A bizarre form of bacterial necrosis in gills of tilapia, Tilapia niloticus and skin lesions in common crap, Cyprinus carpio were identified during the late summer season of the year 2015. Flavobacterium columnare was found to be responsible for pathogenesis in the selected fish of river Yamuna at Allahabad in the eastern region of Uttar Pradesh, India. It was a gram-negative, rodshaped aerobic bacterium. The pattern of infection was very specific and sporadic to host and seasonality. The infection prevalence was recorded more in gills than body surface in both the fish during the period of investigation. All outbreaks occurred at optimum higher water temperature of summer season and it was positively influenced by pollution and medical discharge of neighboring area. The causative bacteria of this report were well documented for fish mortality and diseases to human beings. The present investigation dealt to monitor the pathogenic impact and their consequences for economic value point of view and its alarming causes to public health because investigated water body is related to religion faith.
