In a Danish turbot rearing facility, a severe outbreak of disease was experienced during July and August 1995. Clinical symptoms included anorexia, darkening of the skin and abnormal swimming behaviour. The most prominent pathological findings were multiple skin ulcers, approximately 2 - 10 mm in diameter, similar to those described for infections by typical A. salmonicida. The condition deteriorated into a haemorrhagic septicaemia with high morbidity and mortality. From ulcers and organs of dead fish, pure cultures of typical, brown pigmented Aeromonas salmonicida subsp. salmonicida were recovered. Further laboratory analysis of the isolated strains verified the diagnosis on the basis of biochemical characterization, plasmid profiles and ribotyping. This is the first verified report on outbreak of disease caused by A. salmonicida subsp. salmonicida in non-salmonids in Demmark.