The parasitic isopod fauna of fishes in the southern Caribbean is poorly known. In examinations of 12 639 specimens of 187 species of Venezuelan fishes, the authors found 10 species in three families of isopods (Gnathiids, Gnathia spp. from Diplectrum radiale*, Heteropriacanthus cruentatus*, Orthopristis ruber* and Trachinotus carolinus*; two aegids, Rocinela signata from Dasyatis guttata*, H. cruentatus*, Haemulon aurolineatum*, H. steindachneri* and O. ruber; and Rocinela sp. from Epinephelus flavolimbatus*; five cymothoids: Anilocra haemuli from Haemulon boschmae*, H. flavolineatum* and H. steindachneri*; Anilocra cf haemuli from Heteropriacanthus cruentatus*; Haemulon bonariense*, O. ruber*, Cymothoa excisa in H. cruentatus*; Cymothoa oestrum in Chloroscombrus chrysurus, H. cruentatus* and Priacanthus arenatus; Cymothoa sp. in O. ruber; Livoneca sp. from H. cruentatus*; and Nerocila fluviatilis from H. cruentatus* and P. arenatus*). The Rocinela sp. and A. cf haemuli in the southern Caribbean could represent new species. The abundance of A. cf haemuli appears to have drastically reduced from 1994 to 1999 in the Gulf of Cariaco. The Cymothoa sp. represents an undescribed species that is apparently host specific to O. ruber. It does not occur in the Gulf of Cariaco, but is relatively abundant on the Caribbean coast of Sucre State, Venezuela. The Livoneca sp. is an undescribed species host specific to Diapterus rhombeus, Cymothoa excisa and C. oestrum were thought to have distinct host preferences, but both infected the Heteropriacanthus cruentatus in the present study. Gnathia spp. are reported from Venezuelan waters for the first time. Twenty new host records* are noted. The fish-associated isopod fauna is much more extensive and important than has previously been suspected. Rev. Biol. Trop. 54 (Suppl. 3): 175-188. Epub 2007 Jan. 15.
Keywords: fish-parasitic isopods, Venezuela, new species, new host, new locality records