Outbreaks of phaeohyphomycosis in the chinook salmon (Oncorhynchus tshawytscha) caused by Phoma herbarum.

摘要: Phoma herbarum has been associated with two outbreaks of systemic mycosis in hatchery-reared chinook salmon (Oncorhynchus tshawytscha) fingerlings. Affected fish exhibited abnormal swimming behavior, exophthalmia, multiple rounded areas muscle softening, protruded hemorrhagic vents, and abdominal swelling. In all affected fish, swimbladders were filled whitish creamy viscous fungal mass, surrounded by dark red swimbladder walls, kidneys, musculature. Clinical histopathological examinations suggest that the infection may have started primarily then spread to gastrointestinal tract, surrounding Consistent microscopical findings included broad septate branched hyaline hyphae, 5–12 µm diameter within swimbladder, stomach, often adjacent blood vessels. Profuse growths woolly brown colonies obtained from kidneys on Sabouraud medium. On corn meal agar formation pycnidia, characteristic spp., was detected 10 days incubation. Morphological molecular analyses identified this fungus as herbarum. This report underscores infections a threat raceway-raised salmon.