Abstract:From May 2004 to September 2005, a survey was conducted in six cases of edwardsiellosis in cultured turbot, Scophthalmus maximus. The dominant strain isolated from diseased turbot was identified as Edwardsiella tarda, basis on its morphology, physiological & biochemical tests and 16S rDNA sequence analysis. Challenging tests by the isolate indicated that it was the causative agent for the edwardsiellosis. The disease had two types of infection, i.e., acute and chronic, and giving different clinical signs. Histopathological analysis revealed that the edwardsiellosis could cause lesions in the kidney, spleen, liver, intestine, gills and skin. The most prominent histopathological characteristics of this disease were the proliferation and infiltration of macrophages in various tissues and organs. The kidney showed the most marked changes i.e., proliferation of microphages, multiple necrosis, exudative fibrin and formation of enormous granuloma, while the organ extremely enlarged and changed to whitish pustule. This is the first report for edwardsiellosis in cultured Scophthalmus maximus, in order to provide reference in health management and disease control. Key words:Scophthalmus maximus;Edwardsiella tarda;bacterial identification; histopathology; 16S rDNA