Different pathologies have been observed in an experimental culture of the flounder Paralichthys adspersus, characterized by inflamed bloody eyes, haemorrhagic areas in the mouth and gills and disintegrated lower jaws. Eight Vibrio strains were isolated as pure cultures prior to antibiotic treatment. The phenotypical characterization of the present isolates identified the Vibrio strains as V. splendidus biotype II (5) and V. anguillarum-like (3). All the Vibrio strains displayed susceptibility to chloramphenicol, oxolinic acid, and timethoprimsulphamethoxazole, and seven strains were susceptible to oxitetracycline.