RESUMO -Os peixes de uma estação de cultivo de tambaquis pararam de se alimentar e começaram a morrer. Um total de 72 peixes foi examinado. Todos os peixes estavam com uma alta infestação intestinal por acantocéfalos. A espécie parasita foi identificada como Neoechinorhynchus buttnerae Golvan, 1956. A prevalência foi de 100%, a intensidade por hospedeiro variou de 30 a 406 e a intensidade média e densidade relativa (abundância) foram de 125, 26. Ocorreu oclusão total do trato intestinal nas altas infestações.Palavras-chave: Acanthocephala; parasitas de peixes; tambaqui; mortalidade de peixes; aquacultura. ABSTRACT -The fishes Colossoma macropomum (Cuvier, 1818) from a farm fish stopped to eat and begun to die. Seventy-two fishes caught were examined. All fishes had a high intesti nal infestation for Acanthocephala. The species was Neoechinorhynchus buttnerae Golvan, 1956. The prevalence was 100%, intensity range 30-406 and mean intensity and relative density (abun dance) were 125,26. In the high infestations occurred the total occlusion of the gut lumen. Massive Infestation by

Foram examinados brânquias, fossas nasais e intestinos de tambaquis (Colossoma macropomum) capturados em duas localidades na Amazônia, próximas aos municípios de Tefé/Coari, no médio rio Solimões, Estado do Amazonas e de Santarém no baixo rio Amazonas, Estado do Pará. Nove espécies de parasitas foram encontradas: três da classe Monogenoidea; Anacanthorus spathulatus, Linguadactyloides brinkmanni e Notozothecium sp.; uma de Trematoda da família Paramphistomidae; uma do filo Acanthocephala, Neoechinorhynchus buttnerae, duas do filo Nematoda, Spirocamallanus sp. e Procamallanus sp. e duas da subclasse Copepoda, Gamidactylus jaraquensis e Perulernaea gamitanae. Foram registradas pela primeira vez parasitando o tambaqui, o monogenético Notozothecium sp., espécimens imaturos da família Paramphistomidae, larvas do nematóide Procamallanus sp. e o copépodo Gamidactylus jaraquensis. Os paranfistomídeos e Procamallanus sp. foram encontrados apenas nos hospedeiros da região de Tefé/Coari. Foi observada pouca variabilidade na composição da parasitofauna do tambaqui, entre os dois locais estudados. As espécies Anacanthorus spathulatus, Notozothecium sp., Neoechinorhynchus buttnerae e Perulernaea gamitanae, apresentaram bom potencial como indicadores biológicos para o tambaqui.

Resumo A especificidade parasitária, áreas de fixação, hospedeiros naturais, índices de infestação e variação sazonal de Dolops striata e Dolops carvalhoi foram estudados durante o período de março de 1979 a março de 1980, na área do Janauacá, um lago de várzea da Amazônia Central. A sazonalidade revelou um estreito relacionamento com a variação do nível da água, sendo que os picos máximos de infestação de D. striata e D. carvalhoi ocorreram na estação de rio cheio (abril, maio) e os picos mínimos na estação de seca (setembro, outubro). O D. carvalhoi apresentou uma baixa especificidade parasitária, foi encontrado parasitando sete espécies de peixes incluídas em quatro famílias, três da Pimelodidae, duas da Serrasalmidae, uma da Characidae e uma da Clupeidae. O D. striata apresentou um alto grau de especificidade parasitária ocorrendo em três espécies de peixes incluídas em uma única família, a Anostomidae. Ambas espécies foram encontradas parasitando a superfície externa do corpo de seus hospedeiros.

Sempre existiu uma grande preocupagao em avaliar-se o impacto das populacoes n?tu rais dos parasitas sobre os peixes, pr i nc i pal mente visando a ampl iar os conhec irnentos iia relacao hospedeiro-parasita e a conhecer as estrategias empregadas pelos diferentes gru pos e os aspectos zoologicos, ecologicos e economicos.

This study evaluated the in vitro and in vivo antiparasitic efficacy of formalin against Dawestrema cycloancistrium, the effects on the physiological response of Arapaima gigas and the residual action on fish muscle after 96 h of exposure. As regards the in vitro assay, 0, 22, 44, 66, 88, 110, 330, 660 and 880 mg L − 1 formalin were tested. After 1 h of exposure to 660 and 880 mg L − 1 formalin, there was a 100% mortality of D. cycloancistrium as well as after 2 h of exposure at 330 and 110 mg L − 1 and 3 h of exposure at 44, 66 and 88 mg L − 1. Concerning the in vivo test, when fish were exposed to formalin at 0, 220, 330, 440 and 550 mg L − 1 , there was 100% survival at all concentrations and exposure times evaluated. Baths of 1 h with 440 and 550 mg L − 1 formalin showed 93.3% and 99.3% efficacy respectively. However, the baths of 12 h with 55 and 66 mg L − 1 formalin had the efficacy of 44.5% and 55.5% respectively. In 1 h baths with 220, 330, 440 and 550 mg L − 1 formalin, hematocrit, hemoglobin, number of total erythrocytes, mean corpuscular volume, mean corpuscular hemoglobin concentration, mean corpuscular hemoglobin, plasma glucose levels, cortisol, total proteins, chloride, calcium, sodium, potassium and magnesium of the fish presented no differences in relation to the control values. However, in baths of 12 h with 33, 44, 55 and 66 mg L − 1 formalin, there was a decrease in hematocrit, plasma levels of calcium and chloride, and increased levels of glucose and cortisol, depending on the concentration of formalin used. In the fish muscle, the formalin residue decreased after 96 h in all concentrations and periods evaluated, returning to values close to the control ones. The results indicate that formalin had its efficacy successfully proved in the treatment against D. cycloancistrium at higher concentrations such as 440 and 550 mg L − 1 formalin and shorter exposure time (1 h) without compromising fish homeostasis and consumer food safety. Statement of relevance: The manuscript represents original research on use of formalin in vitro and in vivo for treating infection by monogenoidean Dawestrema cycloancistrium in Arapaima gigas, the giant fish from Amazon. In the fish, muscle the residue levels of formalin after exposure was also investigated. Formalin have efficacy in the treatment against D. cycloancistrium at higher concentrations (440 and 550 mg.L − 1) of formalin and shorter exposure time (1 h) and without compromising A. gigas homeostasis and consumer food safety.

The family Neoechinorhynchidae includes seven species of Neoechinorhynchus from freshwater fishes of Brazil. Although several Neoechinorhynchus species are cited infecting different fish species in Brazil, there is a lack of information concerning to their life cycle and the identification of the intermediate hosts. Thus, the aim of the present study was to describe the development of Neoechinorhynchus buttnerae in its intermediate host collected in a fish farm located in Rio Preto da Eva, Amazonas, Brazil. To verify the presence of N. buttnerae in the fish pond, twenty Colossoma macropomum were captured and analyzed, being corroborated the presence of this parasite species. Samples of plankton were also collected, finding the ostracod Cypridopsis vidua as the intermediate host. For the description of the larvae development, a laboratory experimental procedure was conducted by feeding the collected ostracods with the eggs of the adult specimens taken from the sampled fish. To observe the stages of development an artificial hatch was performed. Every stage of development was photographed, measured, drawn and described. The time of development of the immature stages of N. buttnerae was 29 days, reporting the stages: acanthor, acanthella (with eight developmental changes) and cystacanth. As high infections by N. buttnerae causes morphological damages to the intestine and may compromise the quality of C. macropomum and in consequence the production of fish farmers in the Brazilian Amazon region, the knowledge of its intermediate host and the understanding of its life cycle represents a useful information to prevent and combat infections by this parasite.

No abstract

The aim of this study was to evaluate the impacts of metazoan parasites on hematological and biochemical parameters and relative condition factor of tambaqui (Colossoma macropomum ) farmed in northern Brazil. A total of 32 juvenile fish were captured from a commercial fish farm located in the municipality of Rio Preto da Eva, Amazonas state, Brazil. Parasite prevalence was 100% for Anacanthorus spathulatus, Mymarothecium boegeri and Notozothecium janauachensis, 100% for Neoechinorhynchus buttnerae and 53.13% for Dolops geayi. The greatest mean parasite intensity was found in acantocephalans followed by monogeneans and branchiuran crustaceans. A negative correlation was observed between abundance of N. buttnerae and hematocrit percentage, hemoglobin concentration, total thrombocyte count and glucose and between abundance of the monogenean and glucose concentration. Parasitic infections caused damage in tambaqui in terms of the observed hematological parameters that were characterized by hypochromic anemia and thrombocytopenia, which are important parameters to be used in parasitic diagnosis. This study is the first record of the occurrence of Dolops geayi in farmed tambaqui in the Amazon.