Outbreaks of furunculosis of salmonid fish are often observed at hatcheries in Hokkaido, Japan, when the fish were stored untill to mature. Usually, the outbreaks have been believed to be due to the infection of Aeromonas salmonicida.
The author isolated an etiological agent from the infected fish. To determine the taxonomic position of the isolate, a detailed study was made on morphological and physiological properties. As the results, the isolate was found to be a non-motile Aeromonas. It was different from A. salmonicida or A. salmonicida subsp. achromogenes on the basis as shown in Table 4, to warrant its designation as a new subspecies of A. salmonicida.
(In the next paper, part 2, the name of this subspecies will be proposed.)