Studies on the infection of Nocardia sp. in cultured largemouth bass (Micropterus salmoides , Lacepede)

Abstract

This study describes an investigation on epizootics of nocardiosis of largemouth bass (Micropterus salmoides ) which occurred in southern Taiwan during 1987. The nocardiosis present was found to be a chronic systematic infection in largemouth bass. Several fish showed sluggish swimming, darkening body surface and unilateral or bilateral ulcer. Yellowish nodules scattered throughout gills, operculum, pronephron, liver, spleen, swim bladder and kidneys were observed. The most important target organs for the infection were mainly the pronephron, swim bladder, spleen and kidneys. The presence of aerial hyphae incorporated with the results obtained from biochemical studies may suggest that this bacteria is Nocardia sp