Abstract
From June to August in 1981, an epizootic of mycosis occurred among the abalone (Haliotis sieboldii), which were temporarily held in aquaria with circulating sea water adjusted to 15°C by a cooling system, at an abalone storage facility in Sasebo, Nagasaki Prefecture.
The typical external symptom of diseased abalones was flat or tubercle-like swelling formed on mantle, epipode and dorsal surface of foot.
The mycelium was always observed in the lesions. A fungus was isolated by inoculating materials taken from lesions of diseased abalone onto AMES agar and incubating at 15°C. For the observation of spore discharge, fragments of vegetative hyphae were washed several times with sterile sea water, and then placed in a Petri dish containing sterile sea water. As a result, zoospores formed within the fragment were liberated through the orifice of discharge tube. Encysted spores were spherical, usually 7μm (range of 6 to 10μm) in diameter. The fungus was identified as Haliphthoros milfordensis.
The fungus grew at a temperature range of 4.9 to 26.5°C, with optimum of 11.9-24.2°C.
