Gliding bacteria inflicted fish diseases were prevailing in November and December, but not in May and June. Annual survey of the gliding bacteria revealed that Flexibacter columnaris was common in September and October while other Flexibacter spp. in March and April.
The virulence of these bacteria to eel and tilapia were examined. Methods and conditions for their infection were also studied. In running water, F. columnaris was more virulent to eel than to tilapia, while Flexibacter spp. were more virulent to tilapia than to eel. Artificial infection of gliding bacteria was more effective by contact method than by injection method. Mortality rate of fishes infected with gliding bacteria was high when they were kept in standing water rather than running water post-infection.
Supplement of ferric ion to the artificially infected fishes shortened their survival time. This was more pronounced in fishes infected by injection. However, human transferrin afforded protection to fish against infection with these bacteria.