Examination of the gills of 10 crevalle jack, Caranx hippos (Linnaeus) (Carangidae), from the northeastern portion of Florida Bay, Everglades National Park, Florida revealed 3 species of Heteronchoinea (Monogenoidea): Protomicrocotyle mirabilis (MacCallum, 1918) Johnston & Tiegs, 1922 (Gastrocotylinea, Protomicrocotylidae) (prevalence  =  80%; intensity  =  2–16 parasites/host; mean intensity  =  7 parasites/host); Allopyragraphorus hippos (Hargis, 1956) Yamaguti, 1963 (Microcotylinea, Allopyragraphoridae) (80%; 1–8; 3.5); and Cemocotyle noveboracensis Price, 1962 (Microcotylinea, Cemocotylidae) (80%; 1–100; 35.3). Two crevalle jack (standard length 139–140 mm) were uninfected; 3 (standard length 154–183 mm) had mean intensities (all parasite species) of 14.3 (intensity  =  5–20) parasites per host; 5 larger hosts (standard length  =  312–395 mm) were more heavily infected with the 3 parasite species (mean intensity  =  63.8 [intensity  =  16–109] parasites per host). Protomicrocotyle mirabilis is redescribed and figured; A. hippos is considered a valid species and distinct from Allopyragraphorus incomparabilis (MacCallum, 1917) Yamaguti, 1963 (previously considered synonyms); and C. noveboracensis is distinguished from congenerics in part by lacking a haptoral lappet.