ABSTRACT: Lionfish Pterois volitans are successful invasive predators in the sub-tropical and tropical Western Atlantic. Their invasion of coral reef ecosystems is a major conservation concern, as previous studies in the Western Atlantic have found that this top predator (1) occurs at higher densities and forages more successfully than in its native range, (2) lacks significant predators as an adult, and (3) reduces reef fish recruitment. The effects of lionfish on coral reef communities have been examined, but it is not known if these predators use critical non-reef habitat such as mangroves, which serve as nurseries for many reef fish species. To investigate lionfish usage of non-reef critical habitat, we compared population size-structure and stomach contents of P. volitans in mangroves and coral reefs on the island of San Salvador, Bahamas. In each habitat, >80% of lionfish stomachs contained prey items with similar gut content wet weight (0.98 ± 0.35 g in reef habitat and 0.99 ± 0.43 g in mangrove habitat) despite differences in total lionfish length (231.1 ± 10.30 mm in reef habitat and 176.3 ± 16.83 mm in mangrove habitat). Prey items detected by genetic analysis included individuals of the families Palaemonidae, Penaeidae, Gobidae, Scaridae, Mullidae and Grammatidae. These results demonstrate that lionfish colonize and feed in mangrove habitat in the Bahamas. Further study of lionfish outside reef habitat is required to understand the effects of this marine invasion.