PATHOGENICITY OF THE BACTERIAL ISOLATE AEROMONAS HYDROPHILA TO FISHES IN LABORATORY CONDITIONS

Abstract

The pathogenicity of a bacterial isolate Aeromonas hydrophila recovered from naturally diseased shing fish was investigated against
catfishes (Heteropneustes fossilis and Clarias batrachus) and carp (Channa punctatus) of appropriate average body weights. Two different doses viz. 6.7 × 106 and 6.7 × 105 CFU/fish were injected intramuscularly. Pathogenicity of A. hydrophila was confirmed at water temperature of 30°C by mortality of 60% to 100% of all the tested fishes within 2-11 days. Injected A. hydrophila was re-isolated from liver, kidney and intestine of all the tested fishes. In all the cases of intramuscular injection, external pathology was found. Reddish anal region and fm bases were observed. It was understood that the isolate was a highly virulent pathogen for the challenged fishes.