Background. The observed expansion of the red lionfi sh, Pterois volitans (Linnaeus, 1758), in the Caribbean represents one of the most rapid marine fi sh invasions in the history. The invasion rate of this top predator has resulted in a marked negative effect on local fi sh populations in the Caribbean by impacting local biodiversity. The main aim of this work was to conduct the morphological identifi cation of prey items from the lionfi sh diet, and to determine the spatio-temporal variation of the lionfi sh diet composition in different sites of the Mexican Caribbean, to have a better knowledge of how this invasive species is impacting local species of commercial or ecological importance in the region. Materials and methods. The Mexican Caribbean study area was divided in three zones; North (one locality Isla Contoy), Central (three locations Xpu-Ha, Akumal and X'Cacel), and South (two locations Banco Chinchorro and Xcalak). The fi sh were collected, from different habitats, using SCUBA diving and Hawaiian harpoon. Collected fi sh were taxonomically identifi ed, measured for total length (TL) and standard length (SL), and weighed to the nearest gram. Prey items were identifi ed using a dissection microscope. After identifi cation, prey items were separated, counted, and weighted individually. Finally, statistical analyses were made for all the samples using this study database, containing predators and prey items. Results. A total of 76 prey species were identifi ed in 962 lionfi sh stomachs; 47 of them represented fi shes and 29-crustaceans. Fishes of families Pomacentridae, Labridae, and Scaridae were the most abundant diet components of lionfi sh. Rhynchocinetidae, Penaeidae, and Solenoceridae were the most representative Crustaceans families among the prey items. Molluscs were present as diet components only as incidental food. Conclusion. Red lionfi sh, known for its high competitive capacity, preyed more intensively on fi shes than on crustaceans. Therefore, it is evident that the lionfi sh presence in the Mexican Caribbean may affect mainly the local population of reef fi shes. The presently reported results contribute to a better understanding of the red lionfi sh invasion in the Caribbean.

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