The New Zealand grayling (Prototroctes oxyrhynchus) is an extinct species of fish that was endemic to New Zealand. It was known to the Māori by many names, including pokororo, paneroro, kanae-kura, and most commonly, upokororo. The variety of names for the fish came from either multiple tribes, or to describe the fish at different periods of its life cycle. Even though this fish is named grayling, it is not related to European or American graylings and lacks the large dorsal fin ‘typical’ graylings are characterised by. It is, however, closely related to the Australian grayling (P. maraena). The New Zealand grayling was an amphidromous species, migrating between freshwater and saltwater during different seasons as well as stages in their life cycle. The species was abundant during the 19th century, however, the population decreased during the early 1900s with the last confirmed sighting of the fish being in 1923. In 1951, some years after the last sighting, the species was given full legal protection by the Freshwater Fisheries Regulations. It is the only New Zealand native freshwater fish ever to be protected. In August 2018, the New Zealand Department of Conservation classified the New Zealand grayling as "Extinct" under the New Zealand Threat Classification System. Taxonomy The New Zealand grayling, previously part of the family Prototroctidae, is now part of the family Retropinnidae which contains smelts and graylings found in the southern hemisphere. Previously, smelts and southern graylings were classed into two separate families, Prototroctidae for graylings and Retropinnidae for southern smelts, however, now all six species under these families are classed in Retropinnidae. The fish is part of the genus Prototroctes, which contains two species, the New Zealand grayling (P. oxyrhynchus) and the Australian grayling (P. maraena). Description The New Zealand grayling was a medium-sized fish which, when matured, measured between 30–45 cm in length and slender in shape with the presence of an adipose fin. As an amphidromous fish, during their migration, it was found that graylings, originally silver in colour, would darken to a grey or brown, and turn occasionally gold, while the underbelly remained light. Dentition The dentition of the fish comprises a blunt and rounded snout, with the upper jaw containing a single row of long, blunt teeth that were situated close together forming a comb-like structure. The lower jaw, which contains another single row of smaller and sharper teeth, is slightly shorter than the upper