[1] They are characterised by the presence of a ring of interlocking cytoskeletal denticles, which provide support for the cell and allow for adhesion to surfaces including fish tissue.

In the taxonomy of trichodinids, the exact number, shape and arrangement of the cytoskeletal denticles is critical for determining taxonomic relationships.

Trichodinids are typically found on the gills, skin and fins of fishes, though some species parasitise the urogenital system.

Some species are certainly primary pathogens, however, since they occur in sterile sites (e.g. urinary system), or provoke pronounced responses on the part of the host (e.g. Tripartiella on gills).

High bacterial loads provide abundant food for trichodininds, which subsequently proliferate on hosts and then cause attachment-related pathologies.