RESUMO
This study compared the monogeneans community in C. monoculus from the Tapajós River (state of Pará) and Jari River (state of Amapá), northern Brazil. A total of 2188 monogeneans belonging to eight taxa were collected from the gills of fish: Gussevia arilla, Gussevia longihaptor, Gussevia tucunarense, Gussevia undulata, Sciadicleithrum ergensi, Sciadicleithrum umbilicum, Sciadicleithrum uncinatum and Tucunarella cichlae. Gussevia arilla was the dominant species for C. monoculus from the Tapajós River basin, while S. umbilicum predominated among the hosts from the Jari River basin. For the two populations of C. monoculus, the prevalence, mean intensity and mean abundance of monogeneans were different and the of parasites community had a high qualitative similarity (87.5 %). The monogeneans community of C. monoculus was characterized by high species richness, with infection values varying from low to moderate. The geographic distance and differences in environmental characteristics arising from the same did not influence the richness of species of monogeneans infesting C. monoculus in the Tapajós and Jari rivers, but appear to have been determinants in the differences observed in the structure of the monogenean communities in each region.
RESUMO
Monogeneans are ectoparasites that may cause losses in production and productivity in the aquaculture of Colossoma macropomum. Chemotherapeutics used in aquaculture usually have major adverse effects on fish; hence, the use of essential oils has been considered advantageous, but these are not soluble in water. Thus, the use of nanostructures to enhance water solubility of compounds and improve bioactivity may be very promising. This study investigated the antiparasitic activity of nanoemulsion prepared with Copaifera officinalis oleoresin (50, 100, 150, 200 and 300 mg/L), against monogenean parasites from the gills of C. macropomum. The particle size distribution and zeta potential suggested that a potentially kinetic stable system was generated. The nanoemulsion from C. officinalis oleoresin achieved high efficacy (100%) at low concentrations (200 and 300 mg/L) after 15 min of exposure. This was the first time that a nanoemulsion was generated from C. officinalis oleoresin using a solvent-free, non-heating and low-energy method. Moreover, this was the first time that an antiparasitic against monogeneans on fish gills, based on nanoemulsion of C. officinalis oleoresin, was tested.
Assuntos
Antiparasitários/farmacologia , Caraciformes , Fabaceae/química , Extratos Vegetais/farmacologia , Trematódeos/efeitos dos fármacos , Infecções por Trematódeos/veterinária , Animais , Relação Dose-Resposta a Droga , Emulsões , Doenças dos Peixes/tratamento farmacológico , Doenças dos Peixes/parasitologia , Nanoestruturas/análise , Infecções por Trematódeos/tratamento farmacológico , Infecções por Trematódeos/parasitologiaRESUMO
Outbreaks of diseases pose a major threat to sustainable aquaculture development worldwide. Application of herbal products to combat parasitic diseases provides an alternative approach for sustainable aquaculture. This study investigated the in vitro antiparasitic effects of an oil-in-water nanoemulsion prepared using the essential oil from Pterodon emarginatus, against monogeneans infesting Colossoma macropomum. Gill arches from C. macropomum (47.6 ± 14.5 g and 13.5 ± 1.4 cm) that were naturally parasitized by Anacanthorus spathulatus, Notozothecium janauachensis and Mymarothecium boegeri were immersed in different dispersions of the P. emarginatus nanoemulsions (0, 50, 100, 200, 400 and 600 mg/L). The major compounds presented in the essential oil of P. emarginatus were ß-elemene, ß-caryophyllene and α-humulene. Characterization of these nanoemulsions showed that they have a small mean droplet size and low polydispersity index, which is concordant with stable systems. In this in vitro trial, the P. emarginatus nanoemulsion concentrations of 100, 200, 400 and 600 mg/L presented 100% helminthic efficacy against monogeneans of the gills of C. macropomum. The highest two concentrations used (400 and 600 mg/L) were seen to immobilize the parasites after only 15 min. Therefore, it would be worthwhile testing these concentrations in therapeutic baths against monogeneans of C. macropomum.
Assuntos
Anti-Helmínticos/farmacologia , Caraciformes , Fabaceae/química , Doenças dos Peixes/prevenção & controle , Óleos Voláteis/farmacologia , Trematódeos/efeitos dos fármacos , Infecções por Trematódeos/veterinária , Animais , Emulsões , Doenças dos Peixes/parasitologia , Nanoestruturas/análise , Infecções por Trematódeos/parasitologia , Infecções por Trematódeos/prevenção & controleRESUMO
The present study investigated the occurrence of metacercariae of Ithyoclinostomum dimorphum in Hoplias malabaricus in the basin of the São Francisco River in the state of Minas Gerais (Brazil). Twenty-nine fish were examined in June 2012 during a survey of fish and parasitic fauna. Of the fish examined, 34.5 % had infected eyes, intestine and musculature, with a mean intensity of 1.1 and an abundance of 0.4 per fish. The prevalence in the intestine was 31.0 %, with mean intensity of 1.1 and mean abundance of 0.3. In the eyes, the prevalence was 3.4 %, with a mean intensity of 1.0 and mean abundance of 1.0. The metacercaria found in the right eyeball was lodged between the cornea and iris. The low parasitism did not affect the condition factor (Kn) of the parasitized fish. This was the first report of I. dimorphum in the eyes of Hoplias malabaricus, a secondary intermediate host for this endoparasite.
RESUMO
Hoplias 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.
RESUMO
The present study evaluated the hematological, antiparasitic and growth responses in tambaqui (Colossoma macropomum) fed with diets supplemented with the microalgae Arthrospira platensis and Chlorella vulgaris (0%; 10% A. platensis; 10% C. vulgaris; and 5% A. platensis+5% C. vulgaris). Tambaqui (n=60, 62.57 ± 8.76 g) were fed for 20 days with experimental diets. Blood samples collection was done to determine hematological parameters, and gills were removed to identify and count monogenetic parasites. Supplementation with A. platensis 10% reduced red blood cells count, in consequence mean corpuscular volume and mean hemoglobin concentration increased. Total leukocyte, monocyte, eosinophil, and basophil counts reduced with the use of A. platensis. Higher monocytes, eosinophil, and basophil numbers in tambaqui fed with diet supplemented with 10% C. vulgaris were observed and may have been due to the presence of immunostimulants in this microalga composition. Reduction on total cholesterol in tambaqui that received both microalgae (A. platensis 5%+C. vulgaris 5%) may indicate that combined supplementation presented greater benefits to the health for C. macropomum than separately. Both microalgae were efficient against monogenetic parasites of tambaqui. Thus, the dietary use of the microalgae A. platensis and C. vulgaris provided immunostimulant and antiparasitic efficacy in C. macropomum.
Assuntos
Chlorella vulgaris , Spirulina , Chlorella vulgaris/química , Animais , Suplementos Nutricionais , Caraciformes , Microalgas/químicaRESUMO
The tambaqui (Colossoma macropomum) is a species of great economic importance for fish farming in the Brazilian Amazon, and acanthocephaliasis caused by Neoechinorhynchus buttnerae (Golvan 1956) represents an obstacle to its production due to it causing severe morphological damage to the intestinal mucosa, thus impairing the absorption of nutrients and causing weight loss in the fish. Therefore, the establishment of in vitro protocols for evaluation of anthelmintic drugs is the first step to development of effective measures for in vivo control of this endoparasite. The present study evaluated the in vitro survival of N. buttnerae maintained in Eagle's minimum essential medium under different culture conditions. Three assays were carried out to evaluate whether temperature, supplementation with the antibiotics penicillin and streptomycin, and culture medium replacement or no replacement would influence the motility and morphology of the acanthocephalans. The results of the Kaplan-Meier analysis indicated that the use of culture in minimum essential medium together with penicillin and streptomycin prolonged the parasite's survival when kept at temperatures of 24 °C or 28 °C. We describe herein for first time an alternative protocol that is ideal for the in vitro culture of N. buttnerae. As such, this protocol ensures greater reliability in further in vitro studies with N. buttnerae.
Assuntos
Acantocéfalos , Caraciformes , Animais , Brasil , Reprodutibilidade dos Testes , Aquicultura , Intestinos/parasitologia , Penicilinas/farmacologia , Estreptomicina/farmacologiaRESUMO
The aim of this study was to report the first record of Trichodina heterodentata in banded knifefish Gymnotus carapo. Banded knifefish cultivated in the municipality of Jataí, state of Goiás, in the central western region of Brazil, experienced fish mortality rates of 3-4% per tank. Macroscopic analysis found that fish had lesions on their skin and gills. Smears of the integument and gills were confectioned and air-dried at room temperature and impregnated with silver nitrate to identify the Trichodinidae species causing the lesions. The trichodinid were identified as T. heterodentata, and their characteristics were compared to those from T. heterodentata recorded from other species of host fish. It was observed that the presence of T. heterodentata was associated with inadequate fish management, low water quality, high rates of stocking density, and inadequate nutritional management.
Assuntos
Infecções por Cilióforos , Cilióforos , Gimnotiformes , Oligoimenóforos , Animais , Brasil , Infecções por Cilióforos/veterináriaRESUMO
Blood parameters are useful to measure physiological disturbances in chelonians. Thus they can provide important information for the diagnosis and prognosis of diseases. The aim of this paper was to determine the reference range of plasma glucose, total protein, triglycerides, cholesterol and urea levels, as well as hematocrit, hemoglobin, red blood cell, thrombocyte and white blood cell counts for healthy Podocnemis expansa (Schweigger, 1812), bred in a turtle farm in the Amazonas State, Brazil. Plasma glucose, hemoglobin, mean corpuscular volume (MCV), lymphocytes and heterophils were the parameters with the smallest variations. Significant (p<0.001) correlations between red blood cells count and hematocrit and hemoglobin concentration were found. Turtle P. expansa had lymphocytes, azurophils, heterophils, eosinophils and basophils with morphologic features similar to the ones of others turtles species. No investigated blood parameter was influenced by sex. In further studies, the established reference ranges might be useful for the health assessment of this turtle species.
Assuntos
Tartarugas/sangue , Animais , Contagem de Células Sanguíneas/veterinária , Glicemia/análise , Proteínas Sanguíneas/análise , Colesterol/sangue , Conservação dos Recursos Naturais , Feminino , Hematócrito/veterinária , Hemoglobinas/análise , Masculino , Valores de Referência , Estatísticas não Paramétricas , Triglicerídeos/sangue , Ureia/sangueRESUMO
The objective of this study was to compare and correlate the ecology of neonates and young individuals of Potamotrygon wallacei, Potamotrygon motoro and Paratrygon aiereba with regard to their hematological profile and the physicochemical parameters of the water that they inhabit. Principal component analysis (PCA) on the complete blood count revealed total variation of 72.92%, thus demonstrating a differentiation system for oxygen demand. On the other hand, P. motoro was considered to be an intermediate species, given that its complete blood count characteristics interacted with both P. wallacei and with P. aiereba. The interaction among the biochemical variables was shown to total 64.67% of the factors. This allowed differentiation of P. wallacei from P. aiereba, while P. motoro maintained an intermediate position. These characteristics of differentiation within the preferred environment corroborate the PCA of the present study and confirm that these species can be differentiated through considering the complete blood count and biochemical parameters. The PCA on water properties showed 68.57% differentiation, mainly comprising the x axis (49.44%). It can be affirmed that P. motoro has the capacity to inhabit the preferential areas of P. wallacei and P. aiereba, as well as occupying localities in which other stingrays are not found. In conclusion, P. wallacei presents patterns differentiating it from P. aiereba, while P. motoro is a species that presents intermediate characteristics. The latter can be considered to be a more broadly distributed species regarding its ecophysiological characteristics.
Assuntos
Água Doce/química , Características de História de Vida , Rajidae/fisiologia , Animais , Testes Hematológicos , Rajidae/sangue , Rajidae/crescimento & desenvolvimentoRESUMO
Intraerythrocytic parasites are frequently found in fish, including elasmobranchs. The Amazonian rivers present well defined annual hydrological cycles that results in drastic modifications of the environmental conditions with deep implications in the life cycle of the whole associated biota in those fluvial systems. The freshwater stingray Potamotrygon wallacei (stingray cururu) is a new species restricted to the Middle Rio Negro basin and it is subject to strong alterations in their natural habitats (igapós) a result of the constant variations in the water level of Rio Negro. This work demonstrates the occurrence of intraerythrocytic parasite Cyrilia sp. in this stingray species. Additionally, the prevalence and quantification of hemoparasites in different phases of Rio Negro were also established. Field sampling was carried in the Archipelago of Mariuá, Middle Rio Negro, involving different stages of the water cycle. The intraerythrocytic parasites were quantified by direct counting in blood smears using a total counting of 2000 erythrocytes in each blood smear. The presence of parasites intraerythrocytic generates changes in the morphology of blood cell. The largest amount of the hemoparasites was recorded in the drought period. We observed a decreasing tendency in the number of parasites in the blood between the drought periods and inundation. We concluded that the level of Negro River influences the incidence of intraerythrocytic parasites in the cururu stingray and the drought represents the period of larger susceptibility to the infestation.
Assuntos
Coccídios/isolamento & purificação , Coccidiose/veterinária , Doenças dos Peixes/epidemiologia , Rajidae , Animais , Brasil/epidemiologia , Coccidiose/epidemiologia , Coccidiose/parasitologia , Eritrócitos/parasitologia , Doenças dos Peixes/parasitologia , RiosRESUMO
The aim of this study was to report the first record of Trichodina heterodentata in banded knifefish Gymnotus carapo. Banded knifefish cultivated in the municipality of Jataí, state of Goiás, in the central western region of Brazil, experienced fish mortality rates of 3-4% per tank. Macroscopic analysis found that fish had lesions on their skin and gills. Smears of the integument and gills were confectioned and air-dried at room temperature and impregnated with silver nitrate to identify the Trichodinidae species causing the lesions. The trichodinid were identified as T. heterodentata, and their characteristics were compared to those from T. heterodentata recorded from other species of host fish. It was observed that the presence of T. heterodentata was associated with inadequate fish management, low water quality, high rates of stocking density, and inadequate nutritional management.
O objetivo deste estudo foi relatar o primeiro registro de Trichodina heterodentata em tuviras Gymnotus carapo. Um cultivo de tuviras no município de Jataí, estado de Goiás, na região Centro-Oeste do Brasil, apresentou taxas de mortalidade de peixes de 3-4% por tanque. A análise macroscópica constatou que os peixes tinham lesões na pele e brânquias. Raspados do tegumento e brânquias foram confeccionadas e secas ao ar à temperatura ambiente e impregnadas com nitrato de prata para identificar as espécies de Trichodinidae causadoras das lesões. Os tricodinídeos foram identificados como T. heterodentata, e suas características foram comparadas com as de T. heterodentata registradas para outras espécies de peixes hospedeiros. Observou-se que a presença de T. heterodentata estava associada ao manejo inadequado dos peixes, baixa qualidade da água, altas taxas de densidade de estocagem e manejo nutricional inadequado.
Assuntos
Animais , Controle da Qualidade da Água , Gimnotiformes/parasitologia , Densidade DemográficaRESUMO
Abstract The aim of this study was to report the first record of Trichodina heterodentata in banded knifefish Gymnotus carapo. Banded knifefish cultivated in the municipality of Jataí, state of Goiás, in the central western region of Brazil, experienced fish mortality rates of 3-4% per tank. Macroscopic analysis found that fish had lesions on their skin and gills. Smears of the integument and gills were confectioned and air-dried at room temperature and impregnated with silver nitrate to identify the Trichodinidae species causing the lesions. The trichodinid were identified as T. heterodentata, and their characteristics were compared to those from T. heterodentata recorded from other species of host fish. It was observed that the presence of T. heterodentata was associated with inadequate fish management, low water quality, high rates of stocking density, and inadequate nutritional management.
Resumo O objetivo deste estudo foi relatar o primeiro registro de Trichodina heterodentata em tuviras Gymnotus carapo. Um cultivo de tuviras no município de Jataí, estado de Goiás, na região Centro-Oeste do Brasil, apresentou taxas de mortalidade de peixes de 3-4% por tanque. A análise macroscópica constatou que os peixes tinham lesões na pele e brânquias. Raspados do tegumento e brânquias foram confeccionadas e secas ao ar à temperatura ambiente e impregnadas com nitrato de prata para identificar as espécies de Trichodinidae causadoras das lesões. Os tricodinídeos foram identificados como T. heterodentata, e suas características foram comparadas com as de T. heterodentata registradas para outras espécies de peixes hospedeiros. Observou-se que a presença de T. heterodentata estava associada ao manejo inadequado dos peixes, baixa qualidade da água, altas taxas de densidade de estocagem e manejo nutricional inadequado.
RESUMO
The aim of this study was to report the first record of Trichodina heterodentata in banded knifefish Gymnotus carapo. Banded knifefish cultivated in the municipality of Jataí, state of Goiás, in the central western region of Brazil, experienced fish mortality rates of 3-4% per tank. Macroscopic analysis found that fish had lesions on their skin and gills. Smears of the integument and gills were confectioned and air-dried at room temperature and impregnated with silver nitrate to identify the Trichodinidae species causing the lesions. The trichodinid were identified as T. heterodentata, and their characteristics were compared to those from T. heterodentata recorded from other species of host fish. It was observed that the presence of T. heterodentata was associated with inadequate fish management, low water quality, high rates of stocking density, and inadequate nutritional management.
O objetivo deste estudo foi relatar o primeiro registro de Trichodina heterodentata em tuviras Gymnotus carapo. Um cultivo de tuviras no município de Jataí, estado de Goiás, na região Centro-Oeste do Brasil, apresentou taxas de mortalidade de peixes de 3-4% por tanque. A análise macroscópica constatou que os peixes tinham lesões na pele e brânquias. Raspados do tegumento e brânquias foram confeccionadas e secas ao ar à temperatura ambiente e impregnadas com nitrato de prata para identificar as espécies de Trichodinidae causadoras das lesões. Os tricodinídeos foram identificados como T. heterodentata, e suas características foram comparadas com as de T. heterodentata registradas para outras espécies de peixes hospedeiros. Observou-se que a presença de T. heterodentata estava associada ao manejo inadequado dos peixes, baixa qualidade da água, altas taxas de densidade de estocagem e manejo nutricional inadequado.
Assuntos
Animais , Oligoimenóforos , Infecções por Cilióforos/veterinária , Cilióforos , Gimnotiformes , BrasilRESUMO
The present study evaluates the influence of anesthesia on the parasitic fauna of monogenea fish parasites, as its intensity and viability. Two experiments were conducted: Evaluation of an anesthetic method by sprinkling eugenol directly on gills and evaluation of monogenea motility and viability; Comparison of immersion and directly sprinkling on the gills with benzocaine and eugenol followed by evaluation on parasite intensity. The results suggest that the anesthetic sprinkling didn't interfere in the parasite motility, morphology and body surface integrity analyzed by fluorescence method. The monogenean intensity in the gills was lower in fish anesthetized by immersion method compared to the sprinkling method and the control group. This method of anesthesia can be used in parasitological studies.
Assuntos
Anestésicos/farmacologia , Benzocaína/farmacologia , Caraciformes/fisiologia , Caraciformes/parasitologia , Eugenol/farmacologia , Platelmintos/efeitos dos fármacos , Anestesia/veterinária , Animais , Brânquias/efeitos dos fármacos , Brânquias/parasitologia , Brânquias/fisiologiaRESUMO
Morphological, cytochemical and ultrastructural studies are important to demonstrate the function of the blood cells, which is very little understood in teleosts. In peripheral blood of 'piracanjuba' Brycon orbignyanus, thrombocytes, lymphocytes, monocytes, neutrophils and heterophils were studied and characterized. Thrombocytes had a fusiform or oval shape with PAS-positive granules. Lymphocytes presented small size with sparse basophilic cytoplasm. Monocytes were large in size, presented basophilic cytoplasm that may be foamy or vacuolated, with non-specific esterase staining. The neutrophils presented lightly neutrophilic granule cytoplasm, with positivity for PAS and peroxidase. The heterophils were large in size, with eosinophilic and basophilic granules cytoplasm and PAS-positive. Transmission electron microscopy study demonstrated that the thrombocytes, lymphocytes and monocytes features were similar to other teleosts. In ultrastructural study only one type of neutrophils was observed. Cytochemical findings indicated that neutrophils and monocytes of B. orbignyanus may be involved in phagocytosis, and neutrophils play an important microbicidal role.
Assuntos
Plaquetas/ultraestrutura , Peixes/fisiologia , Leucócitos/ultraestrutura , Animais , Biomarcadores/análise , Plaquetas/química , Grânulos Citoplasmáticos/química , Técnicas Imunoenzimáticas , Leucócitos/química , Microscopia Eletrônica de Transmissão/métodos , Monócitos/química , Monócitos/ultraestrutura , Neutrófilos/química , Neutrófilos/ultraestrutura , Reação do Ácido Periódico de Schiff/métodosRESUMO
A new species of Tripartiella is described from the gills of the wild saddle cichlid Aequidens tetramerus in north Brazil. Wet smears of skin and gills of examined fish were air-dried at room temperature and impregnated with Klein's dry silver method for examination of the adhesive disc's structures and denticles. Total prevalence of parasitism was 65%. This ciliate is characterized as a small-sized trichodinid, body diameter 37.03 ± 4.9 µm, adhesive disc 30.50 ± 2.71 µm, denticulate ring 13.28 ± 0.8 µm and 24 ± 2.0 denticles. Taxonomic and morphometric data for the new species are discussed.
Assuntos
Ciclídeos/parasitologia , Oligoimenóforos/classificação , Animais , Brasil , BrânquiasRESUMO
The prevalence of intestinal parasites and its epidemiological aspects were studied in individuals of both sexes seen at the Outpatient Service of the Municipal Health Center and São Vicente Public Hospital in São José da Bela Vista (SP) from January 1992 to December 1996. The percentage of parasitic infestation was 44.4%, with the occurrence of protozoa and helminths. The high occurrence of parasitism was attributed to the low socioeconomic and educational level of the population and to the precarious hygiene conditions in their households.
Assuntos
Enteropatias Parasitárias/epidemiologia , Brasil/epidemiologia , Escolaridade , Humanos , Higiene , Prevalência , Fatores SocioeconômicosRESUMO
The present work described helminth parasites of curimbatá, Prochilodus lineatus Valenciennes, 1836 from Volta Grande Reservoir, MG, Brazil. Eighteen fishes with average 46.7 +/- 1.1 cm length and 1,674.8 +/- 75.6 g weight were collected. Of the analysed fishes, 15 were parasitized with acanthocephalans in the intestine, showing a prevalence of 83.3%. The helminth was identified as Neoechinorhynchus curemai Noronha, 1973 (Acanthocephala: Neoechinorhynchidae). It differs from other species in dimension of characters and morphology. From the original description of N. curemai, it differs from the biggest dimension of testis, elongated cement gland, nucleated lemnisci, eggs size, larger proboscis hooks length in the middle and in the third circle in males and larger hooks in the anterior circle in females. A smaller percentage occupied by the reproductive system in female trunk was reported. The observation of paratypes of N. curemai of Noronha (1973) showed a great similarity with those of the present work. This fact complements the helminth description from elsewhere.
Assuntos
Acantocéfalos/anatomia & histologia , Peixes/parasitologia , Acantocéfalos/citologia , Acantocéfalos/isolamento & purificação , Animais , Brasil , Feminino , MasculinoRESUMO
Parasite infracommunities were studied in 202 specimens of Astronotus ocellatus collected from a freshwater lake in the State of Amapá, northern Brazil. Relationships between some host attributes (i.e., ontogeny, sex, and body size) and parasite infections were analyzed, but the primary focus was the seasonal variation in the parasite fauna. In total, 6,308,912 parasites belonging to 11 different taxa were found. Protozoa were the most abundant and dominant taxa, but monogeneans, trematode metacercariae, and nematode larvae were also prevalent and abundant. Fish ontogeny had a weak influence on parasite infection rates; juveniles were more parasitized by Dolops nana and Posthodiplostomum sp. The abundances of all parasite species were weakly correlated with host body size (low r(2) values), except D. nana, Contracaecum sp., and Posthodiplostomum sp., which exhibited no correlation between abundance and host body size. Prevalence and abundance were different between flood and drainage seasons for all parasite species, except for D. nana and the 2 metacercarial species. Astronotus ocellatus may represent a link in food-web transmissions for parasites because it is used both as definitive and intermediate host. The parasite fauna of A. ocellatus was composed primarily of ectoparasites, and this could be considered typical of fishes that inhabit lentic waters. Seasonality was a strong determinant in the parasite community structure.