The cornerstone of fisheries management relies on a solid taxonomic base and an understanding of how animals can be grouped into coherent management units. Surprisingly little is known about the basic biology and ecology of opah (Lampris guttatus), a globally distributed species that is commercially exploited and regionally common in the North Pacific. Recent efforts to collect life history data on this species uncovered evidence of two North Pacific morphotypes. Sequencing of the mitochondrial cytochrome c oxidase I gene (655bp) for these morphotypes and other specimens collected worldwide (n=480) produced five strongly diverged and well-supported clades. Additional sequence data from the cytochrome b gene (1141bp) as well as the nuclear recombination activating gene 1 (1323bp) corroborated these results, suggesting these five clades likely represent separate species. Our conclusion that opah is a complex of five separate species has implications for management and indicates a need to gather additional data on these poorly understood fishes.