A total of 311 individual fish from 16 species, 10 Carangidae and 6 Sciaenidae, were examined between August 2004
and February 2007. Twenty one monogenean species from 18 genera and 12 families are reported. Four species, Cemocotylella elongata, Engraulicola cf. thrissocles, Rhamnocercus margaritae, and R. rhamnocercus are reported for the
first time from the Gulf of Mexico; 16 of the parasite-host records are new. Each fish host family is parasitized by a particular set of monogenean species, genera and families not shared with the other.