Occurrence of Heteropolaria lwoffi (Fauré-Fremiet, 1943) and Apiosoma piscicola Blanchard, 1885 (Ciliata) on Salvelinus fontinalis (Mitchill) in Nova Scotia, Canada.

Heteropolaria lwoffi (Faure-Fremiet, 1943) and Apiosoma piscicola Blanchard, 1885 (Ciliata) are reported from fry of Salvelinus fontinalis (Mitchill) at a fish farm in Nova Scotia. The specimens were examined with a scanning electron microscope. Heteropolaria lwoffi attached to pore walls of mucous cells. Apiosoma piscicola had an affinity for the attached scopula of H. lwoffi. Bacterial microcolonies were associated with the adhesive substance secreted by the scopulas but there was no evidence of colony expansion into the underlying skin. The study represents the first specific identifications of stalked peritrichs from salmonids in North America and the first report of A. piscicola on the continent.