New Zealand is a small archipelago at temperate latitudes in the southwestern Pacific Ocean, and has been isolated there since separating from Gondwana about 80 million years ago. Its freshwater fish fauna was discovered beginning with visits by James Cook in the late eighteenth century, and Charles Darwin in the 1830s. Early descriptions of the fauna were by European ichthyologists, but locally domiciled workers took over in the last third of the nineteenth century and the fauna’s taxonomy was substantially clarified by amateur naturalist Gerald Stokell in the 1940s and 1950s. In the modern era the advent of DNA sequencing technology has led to clarification of the taxonomy and the recognition of new cryptic taxa. Additional species have appeared in the fauna towards the end of the twentieth century through natural dispersal and possibly discharges of ships’ ballast water. Today, c. 40 species are recognised, over half in the family Galaxiidae, with the second largest group being Eleotridae. A modest diversity of fossil taxa has been found, mostly from Miocene lake deposits, including at least one belonging to a perciform family not otherwise known from New Zealand.