Study of bacterial haemorrhagic septicaemia causing mortality in Indian major carps from culture ponds of Kolleru lake, Andhra Pradesh, India

Haemorrhagic septicaemia (HS) is a bacterial disease causing severe economic losses in freshwater aquaculture. The present study aimed to isolate, identify, and characterize its pathogen responsible for disease outbreaks and mortality in Indian major carps from ponds in the Kolleru Lake region, India through monthly sampling over eight months. Infected fish exhibited hemorrhages on the body, around the eyes, mouth, ventral surface, fins, and caudal region. Blood, kidney, liver, spleen, and gill tissues were processed for microbiological, biochemical, and molecular analysis. DNA from the isolates was amplified via PCR using primers specific to Aeromonas hydrophila, yielding a ~760 bp product, confirming the pathogen’s presence. This finding establishes A. hydrophila as the causative agent of haemorrhagic septicaemia in Labeo rohita and Catla catla. The results underscore the frequent and significant mortalities in culture ponds caused by bacterial diseases such as haemorrhagic septicaemia and abdominal dropsy, highlighting the need for targeted disease management strategies in aquaculture.