Characterization and Experimental Infection of Vibrio harveyi Isolated from Diseased Asian Seabass (Lates calcarifer)

Abstract

Aims: Vibrio harveyi causes vibriosis to Asian seabass (Lates calcarifer). The disease spreads rapidly among fish stocked in the same cage. It causes high mortality especially in weak and small sized fish stocked at high density in poorly managed net cage. Study to determine the virulence levels of the bacterial pathogen in various aquaculture animals is a key to prevent vibriosis in marine aquaculture. Methodology and Result: Isolation of bacteria from diseased Asian seabass was done using tryptic soy agar (TSA) and thiosulphate citrate bile sucrose agar (TCBS) plates. Virulence of two strains of Vibrio harveyi (VHJR4 and VHJR7) was tested against clinically healthy aquaculture animals. The analysis revealed that the two bacterial strains differ in pathogenicity. The V. harveyi strain VHJR7 was virulent to Asian seabass at 1.40 x 10 4 c.f.u. g -1