Lionfish consume at least 250 fish and crustaceans prey species in the western Atlantic. Main taxa eaten include grunts (Haemulon aurolineatum), wrasses (Thalassoma bifasciatum and Halichoeres spp.), damselfishes (Stegastes partitus and Chromis cyanea), gobies (Coryphopterus personatus), labrisomids (Malacoctenus triangulatus) and Pterois volitans. Because lionfish prey on such a long list of Caribbean reef fauna it should be considered a generalist invasive species that even threats commercially and ecologically important species such as grunts, groupers, snappers, triggerfishes, parrotfishes, surgeonfishes, gobies, lobsters, and cleaner shrimps. Four richness estimators indicate that lionfish may consume around 300 species. Stable isotopes analysis ratifies that most prey eaten by lionfish are reef dwellers. Lionfish diets from the Colombian Caribbean appear distant from the Bahamas and Cayman Island diets in a cluster analysis. Research and monitoring of this dangerous invading species should be maintained.