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In vivo and in vitro antiparasitic activity of the essential oil of Lippia sidoides and blood and histological alterations were assessed in Colossoma macropomum (tambaqui). Essential oil concentrations of 10, 20, 40, 80, 160 and 320mg/L were assayed in vitro against monogenoideans Anacanthorus spathulatus, Notozothecium janauachensis and Mymarothecium boegeri from fish gills. Lippia sidoides essential oil concentrations of 320 and 160mg/L were 100% effective against monogenoideans in 10min and 1h of exposure, respectively. However, the effectiveness of 100% concentrations of 80mg/L and 40mg/L occurred in 3 and 6h, respectively. In the in vivo tests, juvenile fish were submitted to 60min of baths with 10mg/L and 15min of baths with 20mg/L of the essential oil of L. sidoides. These therapeutic baths were not efficient against Ichthyophthirius multifiliis, and monogenoideans present in the gills of C. macropomum. In addition, 10 and 20mg/L of the essential oil of L. sidoides caused an anesthetic effect on the fish and did not influence total glucose and protein plasma levels; however, it decreased the number of total erythrocytes in fish exposed to the higher concentration of this essential oil. Severe alterations and irreversible damage were observed in the fish gills just after L. sidoides essential oil baths and after 24h of recovery. The most recurrent lesions found were hyperplasia and fusion of the lamellar epithelium, vasodilation, detachment of the gill epithelium and lamellar aneurism, epithelial breakdown with hemorrhage, congestion, edema and necrosis, proliferation of the mucous cells and chloride cells and lamellar hypertrophy. Therefore, since the essential oil of L. sidoides has in vitro antiparasitic activity and low concentrations of it have shown toxic effects, the bioactive potential of its main chemical components should be investigated, as well as more efficient forms of its administration in therapeutic baths in order to eliminate fish parasites.

The aim of this study was to investigate parasites crustacean fauna in ,, ,, ,, ,, ,, and of the State Amapá and Pará, in northern Brazil. A total of 242 parasites, including ,, ,, ,, , and undetermined Lernaeidae, were collected from these hosts. The species had the greatest richness among the community of parasitic crustaceans. There was a low abundance of parasites among the hosts, other than, was most abundant in the integument of and. Finally, the present study reported nine new hosts for the crustacean parasite species and expanded knowledge of the occurrence of some parasite species in the Jari River basin, in eastern Amazon.

The aim of this study was to investigate the gills parasites in Satanoperca jurupari from the Jari River, state of Amapá, in eastern Amazon (Brazil). The gills of 100% of the hosts were parasitized by Ichthyophthirius multifiliis (Protozoa), Sciadicleithrum juruparii (Monogenoidea) Genarchella genarchella, Posthodiplostomum sp. (Digenea) Ergasilus coatiarus and Argulus multicolor (Crustacea), and a total of 27,043 parasites were collected. However, the dominance was of I. multifiliis and there was aggregated dispersion of parasites with greater discrepancy for S. juruparii and A. multicolor. Low species richness of parasites (3.1 ± 1.1), low Brillouin diversity index (0.27 ± 0.23), low evenness (0.16 ± 0.13) and high dominance of Berger-Parker (0.88 ± 0.15) were found. The community of parasites in S. jurupari was characterized by low species richness, low diversity and low evenness, with high prevalence and low abundance. The size of host did not have any influence on the parasites community, but the host behavior and availability of infective stages of the parasites were factors structuring the community of ectoparasites found here.Keywords: Aggregation, diversity, freshwater fish, parasites. ResumoO objetivo deste estudo foi investigar a comunidade de parasitos das brânquias de Satanoperca jurupari do Rio Jari, Estado do Amapá, região da Amazônia oriental (Brasil). As brânquias de 100% dos hospedeiros estavam parasitadas por Ichthyophthirius multifiliis (Protozoa), Sciadicleithrum juruparii (Monogenoidea), Genarchella genarchella, Posthodiplostomum sp. (Digenea), Ergasilus coatiarus e Argulus multicolor (Crustacea) e foi coletado um total de 27.043 parasitos. Porém, a dominância foi de I. multifiliis e houve dispersão agregada de parasitos com maior discrepância de S. juruparii e A. multicolor. Foi encontrada uma baixa riqueza de espécies de parasitos (3,1 ± 1,1), baixa de diversidade de Brillouin (0,27 ± 0,23), baixa equitabilidade do índice de diversidade (0,16 ± 0,13) e elevada dominância de 88 ± 0,15). A comunidade de parasitos foi caracterizada por baixa riqueza de espécies, baixa diversidade, baixa uniformidade, alta prevalência e baixa abundância. O tamanho dos hospedeiros não teve influência sobre a comunidade parasitos, mas o comportamento dos hospedeiros e a disponibilidade de formas infectantes dos parasitos foram os fatores estruturando a comunidade dos ectoparasitos encontrados.Palavras-chave: Agregação, diversidade, peixes de água doce, ectoparasitos.

SummaryHoplias malabaricus and Hoplerythrinus unitaeniatus are Erythrinidae family widely distributed in the Amazon River system of great value to both commercial and subsistence fishing for riverine populations. As such, the objective of the present study was to investigate the endoparasite communities of H. malabaricus and H. unitaeniatus of a tributary of the Amazon River in the north of Brazil. The endoparasite communities of H. unitaeniatus and H. malabaricus were taxonomically similar (85%) and consisted of Clinostomum marginatum, Contracaecum sp., Guyanema seriei seriei, Procamallanus (Spirocamallanus) inopinatus, Pseudoproleptus sp. and Gorytocephalus spectabilis, although the dominant endoparasite was C. marginatum, which was the most prevalent and abundant. All the specimens of both H. malabaricus and H. unitaeniatus were parasitized, with a total of 1237 helminths collected in the former host and 1151 helminths collected in the latter. Hoplerythrinus unitaeniatus possessed greater parasite species richness. Both hosts had an aggregate dispersion of parasites, and the abundance of C. marginatum, Contracaecum sp. and G. spectabilis correlated positively with the weight and length of the hosts. The condition factor was not affected by parasitism, but the abundance of C. marginatum and Contracaecum sp. increased when the condition factor of the hosts decreased. This is the first report of G. seriei seriei for H. malabaricus and Pseudoproleptus sp. for H. unitaeniatus.