Abstract
An eel-farm company at Yaizu City imported a large number of elvers of the European Eel from France in the spring of 1969. Through the end of August into September eels grown to 15 to 20cm in body length died at a high mortality rate. Dying eels showed an abnormal swimming action suggestive of suffocation. Observations of eels showing such an action revealed that their gills were infected, without exception, with large numbers of Trichophrya (Fig.15), while it was rarely observed in healthy eels. As Trichophrya had never been reported in the Japanese Eel, this parasite was first suspected of being introduced from France. Afterwards a similar parasite, however, was discovered in high incidences in Japanese eels in ponds in a different district(Fig.6).
This note is the first to describe the suctorian infection of the eel.
