Pathogenicity test of bacterial and fungal fish pathogens in Cirrihinus mrigala infected with EUS disease

Area of Science:

• Ichthyology
• Microbiology
• Aquatic Animal Health

Background:

• Fish diseases pose significant threats to aquaculture sustainability.
• Epizootic Ulcerative Syndrome (EUS) is a major concern for freshwater fish like Cirrihinus mrigala.
• Identifying causative agents is critical for disease management and prevention.

Purpose of the Study:

• To determine the pathogenic effects of various fish pathogens on Cirrihinus mrigala.
• To isolate and identify bacterial and fungal species associated with EUS disease in C. mrigala.
• To evaluate the pathogenicity of isolated microbes through experimental infections.

Main Methods:

• Isolation and biochemical characterization of bacterial and fungal pathogens from diseased C. mrigala.
• Identification of eight bacterial isolates, including Streptococcus grp Q1, Aeromonas hydrophila, Shigella spp., Streptococcus faecalis, Cellobiosococcus sciuri, and Micrococcus luteus.
• Isolation of the fungus Aphanomyces invadens from infected fish.
• In vitro and in vivo pathogenicity testing of isolated microorganisms.

Main Results:

• Six bacterial species were confirmed as pathogenic to C. mrigala.
• Aphanomyces invadens was identified as a fungal pathogen contributing to the disease.
• Experimental infections demonstrated significant pathogenic effects (p < 0.05) of the isolated microbes.
• The study successfully identified key disease-causing agents in C. mrigala.

Conclusions:

• Aeromonas hydrophila, Streptococcus spp., Shigella spp., Cellobiosococcus sciuri, Micrococcus luteus, and Aphanomyces invadens are significant pathogens of Cirrihinus mrigala.
• Understanding these pathogens is vital for developing effective disease control strategies in aquaculture.
• This research provides a foundation for future studies on fish immunology and disease resistance.