Bacterial exoskeletal lesions of the tiger prawn Penaeus monodon.

Tank- and pond-reared Penaeus monodon with exoskeletal lesions were examined. The incidence rate was up to 36% for broodstock in concrete tanks and to 20% for pond-reared prawns. The increase in disease incidence was related to prawn age or duration of culture. Bacterial isolation yielded mostly Vibrio spp. Pathogenicity was tested on healthy P. monodon juveniles by a combination of injury and exposure to the test bacteria. Cumulative mortality was 60% within 72 hours in stabbed prawns and 20-40% after 96 hours for superficially-cut prawns. Growth of the bacteria in culture was active in 0.5-8% NaCl and at 12-40 degree C. In-vitro, test isolates were sensitive to chloramphenicol, furazolidone, nitrofurantoin, oxytetracycline and sulfamethoxazole trimethoprim; and resistant to erythromycin, furanace, kanamycin and streptomycin.