Bacterial isolation was made from shrimps Penaeus monodon showing characteristic
external symptoms of 'black shell disease' from shrimp farms located in southeast coast of India.
The isolates were screened on TeBS agar plates and 0/129 for the selective isolation of Vibrio
sp. Based on the morphological, biochemical and physiological characteristics, the isolate (RJM5)
was characterized as luminescent Vibrio harveyi." Antibiogram of V. Imrueyi indicated that it was
highly sensitive to chloramphenicol. ciprofloxacin, nalidixic acid and streptomycin. The
pathogenicity studies confirmed that the isolate (V.harveyi) was moderately virulent
