Specimens of the parasitic siphonostomatoid copepod Caligus tenuifurcatus Wilson, 1937 were collected from the oral cavity of the yellowfin snook, Centropomus robalito Jordan et Gilbert; the white snook, C. viridis Lockington (Perciformes, Centropomidae), and the yellow snapper, Lutjanus argentiventris (Peters) (Perciformes, Lutjanidae), from a Pacific coastal system of Mexico. Infection was most intense on C. viridis. Caligus tenuifurcatus can be distinguished from its closest congener, C. bonito Wilson, by the body proportions and the basal ornamentation of the medial setae of the second exopodal segment of leg 1. Taxonomic illustrations are provided of both female and male. This is the third record of C. tenuifurcatus; hitherto, it was known only as a parasite of the roosterfish Nematistius pectoralis Gill (Perciformes, Nematistiidae) from Panama and the Gulf of California. Hence, the finding of C. tenuifurcatus as a parasite of two species of centropomids and one species of lutjanid represents a significant expansion of the known host range of this copepod in the eastern tropical Pacific.