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Fish parasites are an important part of aquatic biodiversity and knowing these species and their interactions with their hosts helps in monitoring the aquatic biota. The present study investigated the ectoparasite crustacean fauna of ten fish species from the upper Araguari River, in the state of Amapá, northern Brazil. A total of 508 fish were collected and analyzed from July to November 2014, of which 82.6% (109) were parasitized by one or more crustacean ectoparasite species. In the ten host fish species, a total of 308 ectoparasite specimens were collected, from 12 taxa, such as Argulus multicolor Stekhoven, 1937, Argulus spinulosus Silva, 1980, Argulus sp.1, Argulus sp.2, Argulus sp.3, Dipteropeltis sp., Dipteropeltis hirundo Calman, 1912, Dolops bidentata Bouvier, 1899, Dolops striata Bouvier, 1899 (Argulidae), Braga fluviatilis Richardson, 1911, Braga amapaensis Thatcher, 1996 (Cymothoidae) and Excorallana berbicensis Boone, 1918 (Corallanidae). Higher levels of prevalence and abundance were recorded for Hoplias aimara (Valenciennes, 1847) and Tometes trilobatus Valenciennes, 1850, respectively. These ectoparasites were found in the fins, integument, mouth, and anus of the host fish. Argulus sp.2 and D. bidentata were the most abundant parasites (65.1%), and had the highest species richness. This study registered 36 novel host-parasite interactions, and thus represents a new record for all host species here examined.

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This study investigated the spatial distribution, parasite interactions, and affinities of Branchiura parasites according to macrohabitat and surface type on fish from the Araguari River, Amapá State, in the Brazilian Amazon. This study presents novel information on the interactions of branchiuran species with host fish, and how the morphology of their attachment structures is associated with different host surface morphologies, with and without scales. A total of 558 fish specimens of 26 species were collected, of which 109 fish (10 species) were parasitized by at least one branchiuran parasite; these were selected for further study. The parasites were collected from the buccal cavity, gills, fins, and integument of the host fish. Parasites with suction discs (Argulus) were mainly associated to hosts with small scales and no scales, while parasites with hooks (Dolops) were mainly associated to hosts with large scales. Overall, parasites with suction discs were more specialized per site than those with hooks.

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PURPOSE: This study investigated the anthelmintic efficacy of therapeutic baths with the essential oil of Piper marginatum Jacq against the monogeneans Anacanthorus spathulatus Kritsky, Thatcher & Kayton, 1979, Notozothecium janauachensis Belmont-Jégu, Domingues & Laterça 2004, Mymarothecium boegeri Cohen & Kohn, 2005 and Linguadactyloides brinkmanni Thatcher & Krytsky, 1983 in Colossoma macropomum Cuvier, 1818, and its hematological and histopathological effects on this fish. METHODS: Short six therapeutic baths with 100 mg/L of the essential oil of P. marginatum and two control groups (water from the cultivation tank and water from the cultivation tank + 70% alcohol) were used for 20 min every two days. RESULTS: The therapeutic baths with 100 mg/L of the essential oil of P. marginatum had efficacy of 42.8% against monogeneans of C. macropomum gills. Toxicity was low for C. macropomum, because there were few physiological and histopathological changes that did not compromise the functioning of the gills of this fish. CONCLUSION: Short therapeutic baths with 100 mg/L of the essential oil of P. marginatum had low efficacy for controlling monogeneans in C. macropomum and thus cannot be recommended.

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Over recent years, fish parasites of the genus Cymothoa Fabricius, 1793, have received increased attention due to both their ecological and their economic importance to aquaculture and fishery. As the studies about Cymothoa have increased this improve our understanding on the host specificity and distribution of these parasites. The aim of this paper was to review the current global geographic distribution, distribution patterns and parasite-host interactions patterns of Cymothoa spp. associated with fish from marine and brackish water bodies around the world. A total of 144 samples were analyzed, from which 23 species of Cymothoa were found parasitizing 84 teleost fish species of 35 families and 20 orders. Most of these parasites were found in the mouth of the host fish, including in wild fish. The highest occurrence of parasites was found in host species belonging to the families Carangidae and Lutjanidae. Host specificity was an important factor in the geographic distribution of Cymothoa species as also environmental temperature. Cymothoa indica, Cymothoa exigua and Cymothoa excisa were the species with lowest specificity for host family and widest geographic distribution.

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Abstract Despite being an important component of the freshwater ecosystems and an important factor controlling wild fish populations, Amazonian fish parasites have been poorly studied. Here, we analyzed the fauna of metazoan parasites from 10 detritivorous and omnivorous fish species from Amapá Lake in the western Amazon. Of 159 fish specimens examined, 73.6% were parasitized by one or more species of metazoan parasites. A total of 5,260 parasites (24 Monogenea, 14 Nematoda, 10 Digenea, 2 Acanthocephala, and 6 Crustacea) were identified. Aggregated dispersion pattern of parasites was observed. There was a predominance of endohelminth species that presented a similar pattern regarding the level of component communities (i.e., a low species number, low diversity and dominance of a single species, mainly the digeneans and nematodes in their larval stages). Five species of parasites presented correlation with the body size of the hosts. In the fish community, the presence of endoparasites in the larval and adult stages suggests that these are intermediate, paratenic and definitive hosts, reflecting their detritivorous or omnivorous feeding habits. The trophic level and diet had an influence on the structuring of endohelminth communities and infracommunities. Lastly, 38% of the metazoan parasite species were new records for examined hosts.

Resumo Apesar de ser um importante componente dos ecossistemas de água doce e um importante fator controlador das populações naturais de peixes, os parasitos de peixes amazônicos ainda são pouco estudados. Foi analisada a fauna de parasitos metazoários em 10 espécies de peixes detritívoros e onívoros do Lago Amapá na Amazônia ocidental. Dos 159 espécimes de peixes examinados, 73,6% estavam parasitados por uma ou mais espécies de parasitos metazoários. Um total de 5.260 parasitos (24 Monogenea, 14 Nematoda, 10 Digenea, 2 Acanthocephala e 6 Crustacea) foram identificados. Houve um padrão de dispersão agregado de parasitos. Houve predominância de espécies de endohelmintos que apresentaram padrão semelhante quanto ao nível de comunidades componentes, ou seja, baixo número de espécies, baixa diversidade e dominância de uma única espécie, principalmente os digenéticos e nematoides em estágio larval. Cinco espécies de parasitos apresentaram correlação com o tamanho corporal dos hospedeiros. Na comunidade de peixes, a presença de endoparasitos em fase larval e adulta sugere que esses são hospedeiros intermediários, paratênicos e definitivos, refletindo seus hábitos alimentares detritívoros ou onívoros. O nível trófico e dieta influenciaram na estruturação das comunidades e infracomunidades de endohelmintos. Por fim, 38% das espécies de parasitos metazoários foram novos registros para os hospedeiros examinados.

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This study investigated for the first time the effectiveness of therapeutic baths with essential oil (EO) of Piper hispidum against monogeneans Anacanthorus spathulatus, Notozothecium janauachensis, Mymarothecium boegeri and Linguadactyloides brinkmanni from the gills of Colossoma macropomum, as well as the hematological and histological effects on this fish. In therapeutic baths, 100 mg/L of P. hispidum essential oil and two control groups (water from the culture tank and water from the culture tank with 70% alcohol) were exposed for 1 h/day, with intervals of 48 hours for 3 days, and three replicates each were used. Therapeutic baths with 100 mg/L of P. hispidum essential oil had an efficacy of 78.6% against monogeneans. The toxicity of this essential oil was low, since there were a few physiological and histopathological changes that did not compromise the functioning of the gills of the fish. Therefore, 100 mg/L of P. hispidum essential oil was effective for controlling monogeneans in C. macropomum, when short therapeutic baths were used without compromising the health of the exposed fish.

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Our hypothesis for this study was that annual and seasonal variations do not influence the structure of the component communities and the diversity of metazoan parasites of spinycheek sleeper (Eleotris pisonis) in the Amazon River, state of Amapá, Brazil. A total of 164 fish were collected between 2020 and 2021, from which 888 parasites were found. In 2020, five species of parasites were found (one Nematoda, one Digenea, one Acanthocephala, one Arachnida and one Crustacea); and in 2021, five species were also found (three Nematoda, one Digenea and one Crustacea). Larvae of Contracaecum sp. were the dominant taxon throughout the study. The parasite species richness and Brillouin diversity index were higher in 2021, without significant differences between seasonal periods. Some component communities of parasites showed differences between years and between seasonal periods. These facts do not support the hypothesis that such variables would not influence the component communities of the parasites. Lastly, this report provides the first records of Spirocamallanus inopinatus, Genarchella genarchella, Acari, Ergasilus sp., Neoechinorhynchus sp., larvae of Pseudoproleptus sp. and larvae of Contracaecum sp. in E. pisonis.

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This study evaluated the efficacy of therapeutic baths with Carapa guianensis (andiroba) oil against monogeneans of Colossoma macropomum (tambaqui), as well as the hematological and histological effects on fish. Among the fatty acids identified in C. guianensis oil, oleic acid (53.4%) and palmitic acid (28.7%) were the major compounds, and four limonoids were also identified. Therapeutic baths of 1 hour were performed for five consecutive days, and there was no fish mortality in any of the treatments. Therapeutic baths using 500 mg/L of C. guianensis oil had an anthelmintic efficacy of 91.4% against monogeneans. There was increase of total plasma protein and glucose, number of erythrocytes, thrombocytes, leukocytes, lymphocytes and number of monocytes and decrease in mean corpuscular volume. Histological changes such as epithelium detachment, hyperplasia, lamellar fusion and aneurysm were found in the gills of tambaqui from all treatments, including controls with water of culture tank and water of culture tank plus iso-propyl alcohol. Therapeutic baths with 500 mg/L of C. guianensis oil showed high efficacy and caused few physiological changes capable of compromising fish gill function. Results indicate that C. guianensis oil has an anthelmintic potential for control and treatment of infections by monogeneans in tambaqui.

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This review surveyed information on Caligus Müller, 1785 to identify global infestation patterns and geographic distribution in teleost fishes, as well as physiological and histopathological data and description of treatment strategies. A total 990 samples of Caligus spp. (N = 212 species) obtained of 233 scientific papers on farmed and wild teleost species from 99 families and 30 orders were used, and the highest number of occurrences was on Carangidae. Caligus spp. was predominantly found in marine environments, and only Caligus lacustris and Caligus epidemicus were found in teleost fish of freshwater environments. There was a high prevalence of Caligus spp. on hosts and infestation occurred predominantly in both the tegument and the gills. Caligus species are distributed across different countries and some particularities were identified and discussed. Caligus elongatus and Caligus bonito bonito had the broadest geographic distribution. Histomorphological and hematological disorders caused by infestation by Caligus spp. were reported and discussed, as well as chemotherapeutic products used for controlling and treating the infestations. Variation in the distribution and geographic patterns of Caligus spp. were little evident in many ecosystems and due to the limited data on the infestation of these sea lice on teleost populations in different regions.

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This study aims to report the occurrence of two important parasites in farmed tambaqui Colossoma macropomum in the state of Tocantins, the acanthocephalan Neoechinorhynchus buttnerae and the dinoflagellate protozoan Piscinoodinium pillulare, also suggesting the main treatments to control them. The fish sampled for the study were infected by N. buttnerae, and P. pillulare, with prevalence from 100% and mean intensity from 51.4 to 354,264, respectively. This was the first report on the occurrence of such parasites in C. macropomum in the state of Tocantins. We emphasize the need to adopt good farm management and biosecurity practices to prevent pathogenic agents to enter or leave a property. Reported treatments with synthetic and natural products with positive results are also suggested to treat against those parasites in farmed C. macropomum.

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This study evaluated the efficacy of therapeutic baths with Carapa guianensis (andiroba) oil against monogeneans of Colossoma macropomum (tambaqui), as well as the hematological and histological effects on fish. Among the fatty acids identified in C. guianensis oil, oleic acid (53.4%) and palmitic acid (28.7%) were the major compounds, and four limonoids were also identified. Therapeutic baths of 1 hour were performed for five consecutive days, and there was no fish mortality in any of the treatments. Therapeutic baths using 500 mg/L of C. guianensis oil had an anthelmintic efficacy of 91.4% against monogeneans. There was increase of total plasma protein and glucose, number of erythrocytes, thrombocytes, leukocytes, lymphocytes and number of monocytes and decrease in mean corpuscular volume. Histological changes such as epithelium detachment, hyperplasia, lamellar fusion and aneurysm were found in the gills of tambaqui from all treatments, including controls with water of culture tank and water of culture tank plus iso-propyl alcohol. Therapeutic baths with 500 mg/L of C. guianensis oil showed high efficacy and caused few physiological changes capable of compromising fish gill function. Results indicate that C. guianensis oil has an anthelmintic potential for control and treatment of infections by monogeneans in tambaqui.(AU)

Avaliou-se a eficácia de banhos terapêuticos com óleo de Carapa guianensis (andiroba) contra monogenéticos de Colossoma macropomum (tambaqui), bem como os efeitos hematológicos e histológicos. Dentre os ácidos graxos identificados no óleo de C. guianensis, ácido oleico (53,4%) e ácido palmítico (28,7%) foram os compostos majoritários, e quatro limonoides também foram identificados. Banhos terapêuticos de 1 hora foram realizados por cinco dias consecutivos, não havendo mortalidade de peixes em nenhum dos tratamentos. Banhos terapêuticos, com 500 mg/L de óleo de C. guianensis, apresentaram eficácia de 91,4% contra monogenéticos. Houve aumento dos níveis plasmáticos de proteína total e glicose, número de eritrócitos, trombócitos, leucócitos, linfócitos e número de monócitos e diminuição do volume corpuscular médio. Alterações histológicas, como descolamento do epitélio, hiperplasia, fusão lamelar e aneurisma, foram encontradas nas brânquias de tambaqui de todos os tratamentos, incluindo os controles com água do tanque de cultivo e água do tanque de cultivo + álcool isopropílico. Banhos terapêuticos com 500 mg/L de óleo de C. guianensis mostraram alta eficácia e causaram poucas alterações fisiológicas capazes de comprometer a função branquial dos peixes. Esses resultados indicam que o óleo de C. guianensis apresenta potencial anti-helmíntico para controle e tratamento de infecções causadas por monogenéticos em tambaqui.(AU)

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This study investigated the effects of dietary supplementation with Mansoa alliacea hydroalcoholic extracts on growth, blood and immune parameters of Arapaima gigas. Fish were fed for 30 days with diets enriched with 0, 4, 8, and 12 g kg-1 of M. alliacea hydroalcoholic extract and subjected to infection with Aeromonas hydrophila and handling stress. Fish fed with 8 g kg-1 of extract showed significant increase in final weight, specific growth rate and feed efficiency when compared to the other groups. Glucose, triglycerides, total proteins, and globulins increased significantly in fish fed with 8 g kg-1 of extract, whereas albumin decreased. The number of thrombocytes increased significantly with the dietary supplementation of 8 and 12 g kg-1 of extract. After the challenge with A. hydrophila and handling stress, fish fed with 8 g kg-1 of extract had significantly higher levels of glucose, globulins, and albumins, and fish fed with 8 and 12 g kg-1 of extract showed an increment of respiratory burst. Triglyceride levels dropped significantly in fish fed with 4, 8, and 12 g kg-1 of extract, whereas the number of neutrophils increased, and total thrombocytes, leukocytes and lymphocytes were higher in fish fed with 12 g kg-1 of extract. Dietary supplementation with M. alliacea extract at 8 g kg-1 was efficient in improving the growth and innate immunity of A. gigas, being potentially useful in fish farming to control the development of A. hydrophila infections.(AU)

Investigou-se os efeitos da suplementação com extrato hidroalcólico de Mansoa alliacea sobre o crescimento e parâmetros sanguíneos e imunológicos de Arapaima gigas. Os peixes foram alimentados por 30 dias com dietas enriquecidas com 0, 4, 8 e 12 g kg-1 de extrato hidroalcoólico de M. alliacea e submetidos à infecção por Aeromonas hydrophila e estresse de manejo. Os peixes alimentados com 8 g kg-1 de extrato apresentaram aumento significativo no peso final, taxa de crescimento específico e eficiência alimentar quando comparados aos demais grupos. Glicose, triglicerídeos, proteínas totais e globulinas aumentaram significativamente nos peixes alimentados com 8 g kg-1 de extrato, enquanto a albumina diminuiu. O número de trombócitos aumentou significativamente com a suplementação dietética de 8 e 12 g kg-1 de extrato. Após infecção com A. hydrophila e estresse de manejo, os peixes alimentados com 8 g kg-1 de extrato apresentaram níveis significativamente mais altos de glicose, globulinas e albuminas, e os peixes alimentados com 8 e 12 g kg-1 de extrato apresentaram incremento de explosão respiratória. Os níveis de triglicerídeos decresceram nos peixes alimentados com 4, 8 e 12 g kg-1 de extrato, enquanto o número de neutrófilos aumentou, e o número total de trombócitos, leucócitos e linfócitos foi maior nos peixes alimentados com 12 g kg-1 de extrato. A suplementação com a 8 g kg-1 de extrato de M. alliacea foi eficiente em melhorar o crescimento e a imunidade inata de A. gigas, sendo potencialmente útil na piscicultura para controlar o desenvolvimento de infecções por A. hydrophila.(AU)

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This study aims to report the occurrence of two important parasites in farmed tambaqui Colossoma macropomum in the state of Tocantins, the acanthocephalan Neoechinorhynchus buttnerae and the dinoflagellate protozoan Piscinoodinium pillulare, also suggesting the main treatments to control them. The fish sampled for the study were infected by N. buttnerae, and P. pillulare, with prevalence from 100% and mean intensity from 51.4 to 354,264, respectively. This was the first report on the occurrence of such parasites in C. macropomum in the state of Tocantins. We emphasize the need to adopt good farm management and biosecurity practices to prevent pathogenic agents to enter or leave a property. Reported treatments with synthetic and natural products with positive results are also suggested to treat against those parasites in farmed C. macropomum.(AU)

Este estudo teve como objetivo relatar a ocorrência de dois importantes parasitos em tambaqui Colossoma macropomum cultivado no estado de Tocantins, o acantocéfalo Neoechinorhynchus buttnerae e o protozoário dinoflagelado Piscinoodinium pillulare e também destacar os principais tratamentos para controlá-los. Os peixes examinados estavam infectados por N. buttnerae e P. pillulare, com prevalência de 100% e intensidade média de 51,4 a 354.264,4, respectivamente. Este foi o primeiro relato da ocorrência desses parasitos para C. macropomum no estado de Tocantins. Destaca-se a necessidade da adoção de boas práticas de manejo na produção e de manejo sanitário, para evitar a contaminação da propriedade e a transmissão para pisciculturas vizinhas. Em relação ao controle dessas parasitoses são apresentados os tratamentos com resultados positivos para C. macropomum, com o uso de produtos sintéticos e naturais.(AU)

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Monogenean infestations can cause high mortality in farmed fish and therefore significant economic losses. The present study investigated the efficacy of albendazole in therapeutic baths against monogeneans of Piaractus brachypomus Cuvier, 1818 and Megaleporinus macrocephalus (Garavello & Britski, 1988). For both fish, a 24 hours therapeutic bath with albendazole concentrations of 150, 300 and 500 mg/L were tested against monogeneans from the gills. The baths had an efficacy from 61.4 ± 32.9 (95%CI=64.5) against monogeneans of P. brachypomus, and from 95.4 ± 5.6 (95%CI=10.9) against monogeneans of M. macrocephalus. In P. brachypomus, the hepatosomatic index (HSI) in fish exposed to 150 mg/L of albendazole was higher than in fish exposed to 300 mg/L. The splenosomatic index (SSI) values in fish exposed to 150 mg/L of albendazole were lower than in fish exposed to 300 mg/L. In M. macrocephalus, the HSI and SSI values decreased in treatments with 150, 300 and 500 mg/L of albendazole to control and treat infestations by monogeneans. For M. macrocephalus, 150 mg/L of albendazole can be used to control and treat infestations by monogeneans, while for P. brachypomus 500 mg/L of albendazole can be used in a 24 hours bath.

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This study presents the freshwater and estuarine shrimp species that occur in the state of Amap, in the eastern region of the Brazilian Amazon. The data were obtained through information contained in the Brazilian crustacean collections of the Institute of Scientific and Technological Research of the State of Amap (IEPA) and the National Institute for Research in the Amazon (INPA) and the detailed examination of the listed specimens. All information contained in the log book and specimen labels were noted for the identification and mapping of occurrence areas in the region. A survey in the literature of the species previously recorded for Amap was carried out. The diversity of freshwater and estuarine shrimp was composed of 21 species distributed in the following families: Alpheidae (Alpheus nuttingi), Euryrhynchidae (Euryrhynchus amazoniensis, Euryrhynchus burchelli, Euryrhynchus tomasi and Euryrhynchus wrzesniowskii), Lysmatidae (Exhippolysmata oplophoroides), Palaemonidae (Macrobrachium acanthurus, Macrobrachium amazonicum, Macrobrachium brasiliense, Macrobrachium carcinus, Macrobrachium jelskii, Macrobrachium inpa, Macrobrachium olfersii, Macrobrachium surinamicum, Nematopalemon schmitti, Palaemon carteri, Pseudopalaemon amazoniensis, Pseudopalaemon chryseus, Leander tenuicornis), Penaeidae (Xiphopenaeus kroyeri and Sergestidae) (Acetes marinus and Acetes paraguayensis). Alpheus nuttingi and L. tenuicornis were new records for the state of Amap. This study contributes to the knowledge of the diversity and geographic distribution of decapod crustaceans in Amap and highlights areas where there are gaps in collection, thus contributing to a better understanding of these invertebrates in the region.

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This paper investigated information on monogenean species using 312 scientific papers, to search for infection and geographic distribution patterns in native freshwater fish from Brazil. We used 1,698 samples of 296 fish species of 28 families distributed into Characiformes, Siluriformes, Cichliformes, Gymnotiformes, Perciformes, Mugiliformes, Osteoglossiformes and Clupeiformes, in addition to four hybrid fish. Among the hosts of the different orders and families, the greatest numbers of parasite-host associations were found for species of the families Serrasalmidae, Characidae, Loricariidae, Curimatidae and Anostomidae. The 578 species of monogeneans used in parasite-host interactions were distributed in 86 genera of six five families (Dactylogyridae, Gyrodactylidae, Diplectanidae, Microcotylidae, Ancylodiscoididae and Ancyrocephalidae), but with great predominance of Dactylogyridae species. There was variation in prevalence, intensity and abundance levels of monogeneans species among host fish species, as well as in infection sites that occurred predominantly in external organs. Positive correlations of prevalence, intensity and abundance with body length of hosts were observed. There was geographic distribution pattern of monogeneans limited mostly to two hydrographic basins those being the Amazon River and Paraná River. Just approximately 6% of potential monogeneans have been explored thus far, showing a clear need for further studies on this interesting group of parasites.

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This study investigated the influence of temporal and seasonal (i.e., rainy and dry seasons) in communities and infracommunities of metazoan parasites in Pimelodus ornatus, a Siluriformes from the Amazon River in the state of Amapá, in northern Brazil. A total of 144 fish were collected during 2020 and 2021. In 2020, five species of parasites were found (1 Monogenea, 3 Nematoda, and 1 Cestoda), and in 2021, seven species of parasites were found (1 Monogenea, 3 Nematoda, 1 Cestoda, 1 Digenea, and 1 Crustacea). In 2020, Spirocamallanus inopinatus was dominant, while in 2021, Contracaecum sp. was dominant. Brillouin diversity, species richness, and evenness were higher in 2021. There were differences for some parasite infracommunities between years and between seasonal periods. Brillouin diversity and species richness were higher in the rainy season, but there were no differences in evenness and Berger-Parker dominance between the seasonal periods. Temporal and seasonal variations were mainly influenced by rainfall levels, oxygen levels, and environmental temperature and, later, by the availability of infective stages of parasites in the environment and the size of the hosts. Lastly, the influence of the temporal and seasonal variations on the structure of communities and infracommunities of parasites was weaker than expected due to the low infection rates of the majority of parasites found.

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This study was carried out to evaluate the anthelminthic efficacy of seeds of Cucurbita maxima and Carica papaya for controlling monogeneans in the gills of Leporinus macrocephalus, besides hepatosomatic and splenosomatic index and condition factor of host. The fish were fed with seeds of C. maxima or C. papaya for seven days, and these treatments did not cause any mortality among them. Jainus leporini, Urocleidoides paradoxus, Urocleidoides eremitus and Tereancistrum parvus were the monogeneans found, and their prevalence in fish fed with seeds of C. papaya was 100%, while in fish fed with C. maxima the prevalence was 42.8%. Fish fed with seeds of C. papaya showed decreased in intensity and abundance of monogeneans, while fish fed with seeds of C. maxima presented decreased in abundance. Feeding of L. macrocephalus with seeds of C. maxima or C. papaya had efficacy of 69.6 and 67.8%, respectively. The hepatosomatic index of fish fed with seeds of C. maxima or C. papaya was not affected by the treatments. However, the splenosomatic index and condition factor of fish fed with C. maxima seeds decreased. Seeds of C. maxima and C. papaya may be used for controlling monogeneans of L. macrocephalus in fish farming.

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The aim of this study was to investigate the microhabitat affinities of Ergasilus sp. and Therodamas longicollum on the gills of Leporinus fasciatus ("aracu-piau"), an anostomid fish from the Amazon. A total of 143 specimens of L. fasciatus were examined, of which 35% had their gills parasitized by at least one ergasilid species. A total of 159 specimens of Ergasilus sp. and 97 specimens of T. longicollum were recovered. Both ergasilids species exhibited a greater affinity for attachment in arch 1 of the gills of the host. There was a negative correlation between the abundance of Ergasilus sp. and the abundance of T. longicollum within each gill arch. Analysis of distribution along the gill arch showed a higher occurrence of Ergasilus sp. in Section 5, while T. longicollum occurred mainly in Section 3 of the gills. There was a positive correlation between the abundance of these ectoparasites and the size of the gill arch. Ergasilus sp. occurred only on the filament of the gill arch and exhibited affinity for the proximal region, while T. longicollum occurred only in the gill arch itself. The results reveal that these two parasite species compete in the gills of the host without the overlapping of their niches.

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The aim of this study was to investigate the ecology and diversity of community and infracommunities of metazoan parasites Geophagus altifrons (Heckel, 1840) in Rio Jari, in the state of Amapá, in the eastern Amazon region. From the total of 31 fish examined, 90.3% were parasitized by one or more species, collecting a total number of 806 parasites. The parasites species identified were: Sciadicleithrum geophagi, Posthodiplostomum sp., Procamallanus (Spirocamallanus) inopinatus, Raphidascaris (Sprentacaris) sp., Genarchella genarchella, Gorytocephalus spectabilis and Ergasilus xinguensis. Most of the parasites showed an aggregate dispersion pattern. Brillouin diversity index, uniformity and species richness of parasites were low. The component community of parasites was constituted by ectoparasites and endoparasites, but with a predominance of ectoparasites. The body size of hosts had a low effect on the parasites infracommunities. This first eco-epidemiological study for G. altifrons reports these parasites in a host, for the first time, with the exception of S. geophagi and E. xinguensis.

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