Abstract:
Ulcerative skin lesions were encountered in rainbow trout raised in sea water by a commercial concern in
the Western Cape, South Africa. Grossly, the lesions resembled furunculosis but, histopathologically, they
differed from typical furunculosis in that bacterial colonies were rarely found in the organs, and also the kidneys
and spleens were minimally involved. The causative organism was identified as an achromogenic Aeromonas
salmonicida that shared characteristics with all 3 subspecies, salmonicida, masoucida and achromogenes. This
is the first report of an outbreak of this disease in South Africa.
