Parioglossus marginalis, also known as the blackmargin dartfish,[1] is a species of dartfish native to the brackish waters of the coast of New South Wales, Australia[1] and around the northern part of the North Island and Great Barrier Island in New Zealand,[2] This species may be an introduced species in New Zealand, being brought from Australia in ship's ballast water.[3] This species can reach a length of 3.3cm (01.3inches) SL. It is thought by some workers that Parioglossus neoclaedonicus from New Caledonia may be a synonym of P. marginalis and that the Caroline Islands species Parioglossus verticalis, which is known form just a single specimen, may also be synonymous with this species. To resolve these taxonomic uncertainties molecular studies will be required.