During parasitological surveys in Tasmania (Australia), four introduced fish species were investigated for the presence of trichodinid ectoparasites. Five trichodinid species were found on the skin, fins and gills of two of these fishes, i.e. the tench Tinca tinca Linnaeus, 1758 and the red fin perch Perca fluviatillis Linnaeus, 1758. Four trichodinids are known species for which comparative descriptions are provided, i.e. Trichodina acuta Lom, 1961, T. esocis Lom, 1961, T. lepsii Lom, 1962 and Trichodinella epizootica (Raabe 1950) Šrámek- Hušek, 1953. A fifth species, i.e. Trichodina tunnae sp. n. is described as a new species from the red fin perch. All species are described using silver impregnated and hematoxylin stained specimens.