The effects of submarine canyons and the oxygen minimum zone on deep-sea fish assemblages off Hawai'i

► Fish assemblages of two canyon and slope sites off the Hawai'ian Islands are studied. ► Fish abundances are enhanced in canyons only at some depths. ► Presence of a moderate oxygen minimum zone appear to moderate canyon effects on fish assemblages. ► Higher habitat heterogeneity in canyons partially explains enhanced fish species richness. ► We demonstrate that canyon effects influence fish assemblages on an oligotrophic oceanic island margin.