A Comparative Study of Vibrio Infections in Healthy and Diseased Marine Finfishes Cultured in Floating Cages near Penang, Malaysia

Abstract

A total of 497 healthy and diseased marine finfishes cultured in floating cages near Penang, Malaysia, were examined for bacteria in the kidney and spleen. The fishes examined were juvenile greasy grouper (Epinephelus malabaricus (Bloch and Schneider)) (12 healthy; 87 diseaaed); juvenile Bilver aeabaae (Latescalcarifer (Bloch)) (119; 126); and juvenile and marketable-sized golden snapper (Lutjanus johni (Bloch)) (81; 72). Most of the bacteria iso)ated from both healthy and diseased fishes were identified as Vibrio spp. Five of 12 healthy (42%) and 69 of 87 diseased (79%) juvenile grouper were infected with bacteria. Seven of a total of 13 isolates (54%) from healthy grouper vs. 69 of166 total isolates (58%) from diseased fish were identified as vibrios. For juvenile seabaoo, 45 of119 (38%) healthy and 102 of 126 (81%) diseased fish were infected. Forty-one of109 total isolates (38%) from healtby aeabaao vs. 156 of257 total isolates (61 %) from diseas ed seabass were identified as vibrios. Thirty-four of 81 (42%) healthy marketable-sized and 55 of 72 (76%) diseaaed juvenil e snapper were infected. Of the 65 isolates from healthy snapper, 39 (62%) were vibrios, as were 71 of 96 total isolates (74%) from diseased fish. The species of vibrios obtained from the healthy fishes differed from those occurring in diseased fishes. Diseased. fishes harbored predominately Group I vibrios: grouper (42%), seabass (56%) and snapper (62%), whereas fewer Group I vibrios were found in healthy seabass (12%) and snapper (3%) and none were isolated from grouper. Healthy fishes harbored a more heterogeneous group of vibrios, which belonged predominantly to Groups IV and V.