Quarenta e um espécimes do mandi-amarelo Pimelodus maculatus Lacépède, 1803 (Siluriformes: Pimelodidae) e 54 espécimes do jundiá Rhamdia quelen (Quoy & Gaimard, 1824)(Siluriformes: Heptapteridae) foram coletados no Rio Paraíba do Sul, Volta Redonda, Estado do Rio de Janeiro, entre novembro de 2007 e outubro de 2008. Os peixes foram necropsiados para o estudo das suas infracomunidade de metazoários parasitos. Foram coletadas as mesmas três espécies de metazoários parasitos nas duas espécies de peixes estudadas. Estes foram um monogenético, um nematóide e um hirudíneo. Cucullanus pinnai (Travassos, Artiga e Pereira, 1928) (Nematoda: Cucullanidae) e Aphanoblastella sp. (Monogenea: Dactylogyridae) foram as espécies dominantes com os maiores valores de prevalência em P. maculatus e R. quelen, respectivamente. As espécies de parasitos de P. maculatus e R. quelen apresentaram típico padrão de distribuição superdispersa. Nenhum parasito apresentou correlação significativa entre o comprimento total dos siluriformes estudados e a prevalência e abundância parasitária. A riqueza parasitária apresentou média de 0,87 ± 0,67 (0 - 2) e 0,57 ± 0,56 (0 - 2) em P. maculatus e R. quelen, respectivamente, e sem correlação com o comprimento total dos hospedeiros.

Forty-one specimens of mandi-amarelo Pimelodus maculatus Lacépède, 1803 (Siluriformes: Pimelodidae) and 54 specimens of jundiá Rhamdia quelen (Quoy & Gaimard, 1824) (Siluriformes: Heptapteridae) were collected from the Paraíba do Sul River, Volta Redonda, State of Rio de Janeiro, Brazil between November 2007 and October 2008. These fish underwent necropsy so their infracommunities of metazoan parasites could be studied. The same three species of parasites were collected in the two fish species studied. These were one monogenean, one nematode, and one hirudinean. Cucullanus pinnai (Travassos, Artiga, and Pereira, 1928) (Nematoda: Cucullanidae) and Aphanoblastella sp. (Monogenea: Dactylogyridae) were the dominant species with the highest prevalence in P. maculatus and R. quelen. The parasite species of P. maculatus and R. quelen showed an atypical over-dispersed pattern of distribution. No parasite species showed significant correlation between the body total length of the siluriform hosts and their prevalence and abundance. The parasite species richness showed a mean value of 0.87 ± 0.67 (0 -2) and 0.57 ± 0.56 (0 -2) in P. maculatus and R. quelen, respectively, and no correlation with the body total length.

Sixty specimens of Caranx hippos (Linnaeus, 1766) and fifty-five specimens of Caranx latus Agassiz, 1831 collected from the coastal zone of the State of Rio de Janeiro (21-23ºS, 41-45ºW), Brazil, from October 1998 to October 1999, were necropsied to study their metazoan parasites. All specimens of C. hippos were parasitized, and the majority of specimens of C latus (96.4%) were parasitized by one or more metazoan species. Nineteen species of parasites were collected in C. hippos: 5 digeneans, 5 monogeneans, 2 cestodes, 5 nematodes, and 2 copepods. Seventeen species of parasites were collected in C. latus: 6 digeneans, 2 monogeneans, 3 cestodes, 4 nematodes, and 2 copepods. The endoparasites (digeneans, cestodes, and nematodes) were the majoriry, 76.4% and 63.3%, of the total number of parasite specimens collected in C. hippos and C. latus, respectively. The monogeneans Allopyragraphorus hippos (Hargis, 1956) and Cemocotyle carangis (MacCallum, 1913) were the most dominant species with the highest parasitic prevalence in the parasite community of C. hippos and C. latus, respectively. The metazoan parasites of the two host species showed the typical overdispersed pattern of distribution. Bucephalus varicus Manter, 1940. A. hippos, Protomicrocotyle mirabilis (MacCallum, 1918), Cucullanus pulcherrimus Barreto, 1918, and Lemanthropus giganteus KrΦyer, 1863 had a positive correlation only between the host's total length and abundance andlor prevalence in C. hippos. Bucephalus varicus, Tergestia pectinata (Linton, 1905), C. carangis, and Pseudoterranovo sp. had a positive correlation between the host's total length and abundance and/or prevalence in C. latus. In C. hippos, the copepod Caligus robustus Bassett-Smith, 1898 had the highest values of prevalence and abundance in the female hosts. No parasite species showed influence of the host's sex on their prevalence and abundance in C. latus. The mean diversity and the parasite species richness of the parasite infracommunities of C. hippos and C. latus were not significantly different. Only the parasite species diversity of C. hippos was correlated with the host's total length; in both host species the parasite diversity did not showed differences in relation to the sex of the host. Only one pair of ectoparasite species, A. hippos - P. mirabilis, showed significant positive co-occurrence and covariation in the parasite infracommunities of C. hippos. Two endoparasite species, B. varicus - Parahemiurus merus (Linton, 1910), showed negative co-occurrence and positive covariation; and the pair B. varicus - Pseudoterranova sp. had positive co-occurrence and covariation in the infracommunities of C. latus. The values of qualitative and quantitative simila rity coefficients between the parasite communities of C. hippos and C. latus were 55.5 and 30.4, respectively. The parasite communities of C. hippos and C. latus were defined as closest to isolationist type because there are few evidences of interspecific associations or covariations. Additional parasitological studies on other species of carangid fishes from the South American Atlantic Ocean are needed to evaluate the structure of carangid parasite communities in the Neotropical region.