Mesophotic coral ecosystems, which occur at depths of ~40 to 150m, have received recent scientifc attention as potential refugia for organisms inhabiting deteriorating shallow reefs. These ecosystems merit research in their own right, as they harbor both depth-generalist species and a distinctive reef-fsh fauna. Reef ecosystems just below the mesophotic are globally underexplored, and the scant recent literature that mentions them often suggests that mesophotic ecosystems transition directly into those of the deep sea. Through submersible-based surveys in the Caribbean Sea, we amassed the most extensive database to date on reef-fsh diversity between ~40 and 309m at any single tropical location. Our data reveal a unique reef-fsh assemblage living between ~130 and 309m that, while taxonomically distinct from shallower faunas, shares strong evolutionary afnities with them. Lacking an existing name for this reef-faunal zone immediately below the mesophotic but above the deep aphotic, we propose “rariphotic.” Together with the “altiphotic,” proposed here for the shallowest reef-faunal zone, and the mesophotic, the rariphotic is part of a depth continuum of discrete faunal zones of tropical reef fshes, and perhaps of reef ecosystems in general, all of which warrant further study in light of global declines of shallow reefs.