New information on the marine parasitic crustaceans from the Campeche coast, Gulf of Mexico (GoM), can improve our baseline knowledge of the ecology of both the host and parasite by providing, for example, parameters of infection. Such knowledge is especially important for fish farming, so that appropriate quarantine measures can be established. Our aim was to morphologically identify the parasitic crustaceans infecting puffer fish of commercial importance in the coastal zone of Campeche, Mexico. We provide new information on four known species of parasitic crustaceans from 92 specimens representing five species of tetraodontid fish. The parasitic crustaceans Argulus sp. (Branchiura, Argulidae), Caligus haemulonis (Caligidae), Pseudochondracanthus diceraus (Chondracanthidae), and Taeniacanthus lagocephali (Taeniacanthidae) (all Copepoda) were found on Lagocephalus laevigatus, Sphoeroides nephelus, S. parvus, S. spengleri, and S. testudineus. This study revealed the occurrence of P. diceraus, which is of importance in aquaculture, on Sphoeroides annulatus in the Mexican Pacific. Additionally, our results and other documentary records provide the first evidence of the interoceanic occurrence of the same parasitic crustacean species in the south-southwest of Gulf of Mexico, the Atlantic Ocean, and the Pacific Ocean. Moreover, our study provides valuable information on the biodiversity of parasitic crustaceans present in the GoM on puffer fish which are of great commercial importance for human consumption, fisheries, and aquaculture.