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The pirarucu (Arapaima gigas) is a fast-growing Amazonian species of high commercial value. The present study aimed to determine the dietary crude protein (CP) level to promote maximum zootechnical performance for pirarucu fingerlings and as their resistance to Aeromonas hydrophila, as well as evaluate their hematological parameters. Pirarucu fingerlings (2.4 ± 0.08 g, 6.8 ± 0.52 cm) were distributed in 18 tanks (140 L, 40 fish per tank, n = 3) and fed six experimental diets consisting of increasing levels of CP: 300, 400, 450, 500, 550 and 650 g kg-1 in a completely randomized design. Data were submitted to one-way ANOVA (p < 0.05) and the ideal CP level for weight gain was determined using polynomial regression analysis. The dietary CP levels were evaluated using a quadratic polynomial regression and the level of 595 g kg-1 was determined for the best weight gain. The hematocrit of fish fed 300 g kg-1 was higher than in the other groups. No mortalities were observed after the 15-day bacterial challenge; however, number of pirarucu with bacterial damage on the pirarucu caudal fin was higher in the group that was fed the diet with 300 g kg-1. A dietary protein level of 618 g kg-1 is therefore recommended for providing maximum weight gain and immunological resistance in pirarucu fingerlings weighing 2.4-112.5 g.

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Ammonia is toxic to fish, and when associated with global warming, it can cause losses in aquaculture. In this study, we investigated the physiological and zootechnical responses of Arapaima gigas to the current scenarios and to RCP8.5, a scenario predicted by the IPCC for the year 2100 which is associated with high concentrations of environmental ammonia (HEA). Forty-eight chipped juvenile A. gigas were distributed in two experimental rooms (current scenario and RCP8.5) in aquariums with and without the addition of ammonia (0.0 mM and 2.44 mM) for a period of 30 days. The HEA, the RCP8.5 scenario, and the association of these factors affects the zootechnical performance, the ionic regulation pattern, and the levels of ammonia, glucose, triglycerides, sodium, and potassium in pirarucu plasma. The branchial activity of H+-ATPase was reduced and AChE activity increased, indicating that the species uses available biological resources to prevent ammonia intoxication. Thus, measures such as monitoring water quality in regard to production, densities, and the feed supplied need to be more rigorous and frequent in daily management in order to avoid the accumulation of ammonia in water, which, in itself, proved harmful and more stressful to the animals subjected to a climate change scenario.

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In a previous work, the common gonadotrophic hormone α-subunit (ag-GTHα), the ag-FSH ß- and ag-LH ß-subunit cDNAs, were isolated and characterized by our research group from A. gigas pituitaries, while a preliminary synthesis of ag-FSH was also carried out in human embryonic kidney 293 (HEK293) cells. In the present work, the cDNA sequence encoding the ag-growth hormone (ag-GH) has also been isolated from the same giant Arapaimidae Amazonian fish. The ag-GH consists of 208 amino acids with a putative 23 amino acid signal peptide and a 185 amino acid mature peptide. The highest identity, based on the amino acid sequences, was found with the Elopiformes (82.0%), followed by Anguilliformes (79.7%) and Acipenseriformes (74.5%). The identity with the corresponding human GH (hGH) amino acid sequence is remarkable (44.8%), and the two disulfide bonds present in both sequences were perfectly conserved. Three-dimensional (3D) models of ag-GH, in comparison with hGH, were generated using the threading modeling method followed by molecular dynamics. Our simulations suggest that the two proteins have similar structural properties without major conformational changes under the simulated conditions, even though they are separated from each other by a >100 Myr evolutionary period (1 Myr = 1 million years). The sequence found will be used for the biotechnological synthesis of ag-GH while the ag-GH cDNA obtained will be utilized for preliminary Gene Therapy studies.

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The increasing prevalence of multi-drug resistant (MDR) Escherichia coli in distinct ecological niches, comprising water sources and food-producing animals, such as fish species, has been widely reported. In the present study, quinolone-resistant E. coli isolates from Arapirama gigas, a major fish species in the Brazilian Amazon rivers and fish farms, were characterized regarding their antimicrobial susceptibility, virulence, and genetic diversity. A total of forty (40) specimens of A. gigas, including 20 farmed and 20 wild fish, were included. Thirty-four quinolone-resistant E. coli isolates were phenotypically tested by broth microdilution, while resistance and virulence genes were detected by PCR. Molecular epidemiology and genetic relatedness were analyzed by MLST and PFGE typing. The majority of isolates were classified as MDR and detected harboring blaCTX-M, qnrA and qnrB genes. Enterotoxigenic E. coli pathotype (ETEC) isolates were presented in low prevalence among farmed animals. MLST and PFGE genotyping revealed a wide genetic background, including the detection of internationally spread clones. The obtained data point out A. gigas as a reservoir in Brazilian Amazon aquatic ecosystems and warns of the interference of AMR strains in wildlife and environmental matrices.

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This study investigated the in vitro and in vivo efficacy of trichlorfon against Dawestrema cycloancistrium, as well as its physiological effects on arapaima. Naturally parasitized arapaima gill arches were exposed in vitro to 100, 250, 500 and 750 mg/L of trichlorfon and a control group (only distilled water), in triplicate. Parasites were monitored, and mortality was used to determine the median effective concentration (EC50 ). The 750 mg/L concentration demonstrated 100% in vitro efficacy against D. cycloancistrium after 60 min, while the intermediate (500 mg/L) and the lowest (100 and 250 mg/L) tested concentrations were completely efficient after 90 and 130 min, respectively. The EC50-1h of trichlorfon for D. cycloancistrium was determined at 171.73 mg/L. Parasitized arapaima juveniles were exposed to a control group and 150 mg/L of trichlorfon in triplicate. Fish were exposed to two therapeutic baths for 60 min with 24-h intervals between treatments. Therapeutic baths with 150 mg/L of trichlorfon were 92.99% effective against D. cycloancistrium and did not bring about haematological alterations (erythrogram, white blood cell count, thrombogram, plasma glucose and total proteins). Therefore, 150 mg/L of trichlorfon can be used in therapeutic baths to control and treat D. cycloancistrium infestations with no physiological impairments for arapaima.

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Handcrafted salted fish is marketed weekly in retail markets and public fairs in the Porto Velho city, Rondônia sate, Brazil. Knowing the microbiological quality of these products is essential for public health, given that such products are not subject to any quality control. The aimed of the study was to evaluate the hygienic-sanitary characteristics and the moisture content of pirarucu and salted and dried shrimp marketed in the Porto Velho city. Twenty samples were collected, 10 pirarucu and 10 shrimp, in February and June 2019. For microbiological analysis, surface plating was performed using acidified potato agar, for molds and yeasts, and PCA agar for halophilic bacterias. Moisture was determined by gravimetry, using an oven at 105° C. Results for molds and yeasts on pirarucu ranged <10 log CFU/g (absent) to 3 log CFU/g. For shrimp, values ranged <10 log CFU/g to 3.57 log CFU/g. For halophilic bacterias, contents ranged <10 log CFU/g to 6.30 log CFU/g in pirarucu samples and <10 log CFU/g to 6.97 log CFU/g in shrimp samples. The variation in moisture content ranged 36.99 to 54.31% for pirarucu, and 40.6 to 56.82% for shrimp. The results obtained may be related to poor hygienic conditions in processing, the lack of hygiene of utensils and places for handling, or even the quality of the raw material used.(AU)

Pescado salgado preparado artesanalmente é semanalmente comercializado em mercados varejistas e feiras públicas na cidade de Porto Velho, Rondônia. Conhecer a qualidade microbiológica desses produtos é essencial para a saúde pública, haja visto, que tais produtos não estão sujeitos a nenhum controle de qualidade. O objetivo do estudo foi avaliar as caracterís-ticas higiênico-sanitárias e o teor de umidade de pirarucus e camarões salgados e secos comercializados em Porto Velho. Foram coletadas 20 amostras, 10 de pirarucu e 10 de camarão, em fevereiro e junho de 2019. Para as análises microbiológicas foi realizado o plaqueamento em superfície usando-se ágar batata acidificado, para bolores e leveduras, e ágar PCA para as bacté-rias halofílicas. A umidade foi determinada por gravimetria, com uso de estufa a 105°C. Os resultados para bolores e leveduras em pirarucu variaram de <10 log UFC/g (ausente) a 3 log UFC/g. Para os camarões os valores variaram de <10 log UFC/g a 3,57 log UFC/g. Para as bactérias halofílicas os teores variaram de <10 log UFC/g a 6,30 log UFC/g nas amostras de pirarucu e de <10 log UFC/g a 6,97 log UFC/g nas amostras de camarão. A variação nos teores de umidade foi de 36,99 a 54,31% para o pirarucu, e de 40,6 a 56,82% para o camarão. Os resultados obtidos podem estar relacionados às más condições higiênicas no processamento, à falta de higiene dos utensílios e dos locais de manipulação, ou ainda, à qualidade da matéria-prima empregada.(AU)

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The study of the functional anatomy of the digestive system of fish, in particular the oropharyngeal cavity, is of great importance because it allows inferences about the feeding habit, mechanisms of capture, selection, and processing of food carried out by different species. Thus, the aim of this stu-dy was to describe the anatomical adaptations of the oropharyngeal cavity of the pirarucu (Arapai-ma gigas Schinz, 1822) using scanning electron microscopy (SEM) techniques. The oropharyngeal cavity of six specimens of pirarucu was collected in juvenile phase, from Aquaculture Research Cen-ter at the Universidade Federal de Rondônia (UNIR), created for commercial purposes. The anato-mical pieces were fixed in 10% buffered formalin and processed for SEM analysis. Anatomically, the oropharyngeal cavity of the pirarucu is composed of five pairs of branchial arches, apical portion of the tongue, floor of the tongue, lower pharyngeal area, and upper pharyngeal plate. In SEM, we observed that the mucosa of the apex of the tongue and the upper pharyngeal roof have a smooth texture and are covered by squamous cells with numerous small openings scattered over the surfa-ce. The portions of the floor of the tongue and the lower pharyngeal area, on the other hand, have adaptations in the form of a projectile and numerous sensory papillae, giving a rough texture to the region. Thus, the oropharyngeal cavity of pirarucu is adapted for the capture, apprehension, and swallowing of its prey, with signs of carnivory.(AU)

O estudo da anatomia funcional do aparelho digestivo dos peixes, em particular da cavidade orofa-ríngea, é de grande importância, pois permite inferências sobre o hábito alimentar, mecanismos de captura, seleção e processamento de alimentos realizados por diferentes espécies. Assim, o objetivo do estudo foi descrever as adaptações anatômicas da cavidade orofaríngea do pirarucu (Arapaima gigas Schinz, 1822) por meio de técnicas de microscopia de varredura eletrônica (MEV). A cavidade orofaríngea de seis espécimes de pirarucu foi coletada na fase juvenil, no Centro de Pesquisa em Aquicultura da Universidade Federal de Rondônia (UNIR), criado para fins comerciais. As peças anatômicas foram fixadas em formalina tamponada a 10% e processadas para análise em MEV. Ana-tomicamente, a cavidade orofaríngea do pirarucu é composta por cinco pares de arcos branquiais, porção apical da língua, assoalho da língua, região faríngea inferior e placa faríngea superior. Na MEV, a pesquisa observou que a mucosa do ápice da língua e o teto faríngeo superior possuem textura lisa e são recobertos por células escamosas com numerosas pequenas aberturas espalha-das pela superfície. As porções do assoalho da língua e da região faríngea inferior, por outro lado, apresentam adaptações em forma de projétil e numerosas papilas sensoriais, conferindo textura áspera à região. Assim, a cavidade orofaríngea do pirarucu é adaptada para a captura, a apreensão e a deglutição de sua presa, com sinais de carnivoria.(AU)

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The objective of this study was to investigate the parasites occurrences and to determine the rates of infestation/parasitic infection in juvenile Arapaima gigas from seven fish farms in the state of Amazonas, relating to the characteristics of these fish farms. Of the 70 A. gigas evaluated, 43 were infested/infected, with a total of 133 parasites collected. Three fish farms (2, 4, 6) showed the highest levels of prevalence of parasites (100%, 70%, 70%), mean intensity (4.1±2.6, 8.1±9.2, and 2.1±1.3), and mean abundance (4.1±2.6, 5.7±8.1, and 1.5±1.5), respectively. Prevalence ranged from 30% to 100%, mean intensity from 1.0 to 8.1 and mean abundance from 0.3 to 5.7. Monogenea, Digenea, Nematoda (Hysterothylacium sp. and Spirocamallanus sp.) and Acanthocephala (Neoechinorhynchus sp. and Polyacanthorhynchus sp.) were identified. The parasites Hysterothylacium sp. and Neoechinorhynchus sp. were the most prevalent parasites with 31.43% and 15.71%, respectively. The fish presented negative allometry in growth and constant condition factor. Measures to prevent and control the parasitic diseases diagnosed are discussed as well prophylactic practices that contribute to the biosecurity of the farms.(AU)

O objetivo deste trabalho foi investigar as ocorrências de parasitos e determinar as taxas de infestação/infecção parasitária em juvenis de Arapaima gigas de sete pisciculturas do Estado do Amazonas, relacionando às características dessas pisciculturas. Dos 70 A. gigas avaliados, 43 estavam infestados/infectados, com um total de 133 parasitos coletados. As pisciculturas 2, 4 e 6 apresentaram os maiores níveis de prevalência de parasitas (100%, 70%, 70%), intensidade média (4,1±2,6, 8,1±9,2 e 2,1±1,3) e abundância média (4,1±2,6, 5,7±8,1 e 1,5±1,5), respectivamente. A prevalência variou de 30% a 100%, intensidade média de 1,0 a 8,1 e abundância média de 0,3 a 5,7. Monogenea, Digenea, Nematoda (Hysterothylacium sp. e Spirocamallanus sp.) e Acanthocephala (Neoechinorhynchus sp. e Polyacanthorhynchus sp.) foram identificados. Os parasitas Hysterothylacium sp. e Neoechinorhynchus sp. foram os mais prevalentes com 31,43% e 15,71%, respectivamente. Os peixes apresentaram alometria negativa no crescimento e fator de condição constante. Foram discutidas as medidas de prevenção e controle das doenças parasitárias diagnosticadas, assim como práticas profiláticas que contribuam para a biossegurança das fazendas.(AU)

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Arapaima gigas, one of the world's largest freshwater fish, is considered an emerging species for aquaculture development in Brazil given its high growth rate and meat quality. However, the lack of reproductive control in captivity has limited the expansion of Arapaima farming. This study aimed to test the effects of hormonal induction using mGnRHa implants and size pairing on broodstock reproduction through the analyses of sex steroids. To do so, broodstock of different sizes (large, small or mixed) were paired and implanted. Plasma and cephalic secretion profiles of testosterone (T), 11-ketotestosterone (11-KT) and 17ß-oestradiol (E2) were analysed. Compared to control (non-implanted), implanted broodstock showed a significant increase in plasma 11-KT (large and small males) and T (large and mixed females) post GnRHa implantation. In females, a significant increase in plasma T levels was shown, however, E2 remained unchanged after implantation. Despite the lack of clear spawning induction, this study showed the potency of GnRHa on sex steroid production regardless of pairing groups. Interestingly, significant correlations between blood plasma and cephalic secretion levels of 11-KT in males and T in females were observed, indicating the possible release of pheromones through the cephalic canals of A. gigas.

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The Lower Amazon region (Western Pará, northern Brazil) is greatly affected by mining exploitations (particularly artisanal gold mines) and other industrial and intensive agricultural activities with potentially strong impacts on aquatic ecosystems. Although such impacts include contamination with various toxic elements, to date only the effects of Hg have been considered. In this study, toxic and trace element concentrations were determined in the flesh of 351 fish specimens, including detritivores (Acarí, Pterygoplichthys pardalis), omnivores (Piranha, Pygocentrus nattereri; Pirarucu, Arapaima sp.) and carnivores (Caparari, Pseudoplatystoma fasciatum; Tucunaré, Cichla ocellaris), during the dry and wet seasons in 2015 and 2016. The range of concentrations of toxic element residues were 2-238 µg/kg fresh weight for As, 1-77 µg/kg for Cd, 4-1922 µg/kg for Hg and 1-30 µg/kg for Pb. Only the maximum concentrations of Hg established in the Brazilian legislation for fish destined for human consumption (0.5 mg/kg) were exceeded (in 16% of carnivorous species). The large between-species and seasonal differences observed for all these toxic elements are probably related to the seasonal behaviour and dietary habits of the different fish species. By contrast, essential trace element concentrations were low and not related to seasonal or dietary factors, and the observed differences may be at least partly related to the metabolism of each species. The associations between Hg and the essential trace elements Se, Fe, Co and Mn deserve special attention, as these trace elements may play a role in Hg cycling and methylation and merit further evaluation with the aim of reducing Hg toxicity in aquatic environments.

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O pirarucu (Arapaima gigas) é um peixe carnívoro da Amazônia e é considerado um dos peixes mais importantes da região. Ele é manejado de forma sustentável por Acordos de Pesca da Reserva de Desenvolvimento sustentável Mamirauá. Dados microbiológicos são necessários para verificar a qualidade higiênico-sanitária dos peixes manejados nessa região. Devido a essa importância o presente trabalho teve como objetivo avaliar a qualidade microbiológica do pirarucu manejado nas Reservas de Desenvolvimento Sustentável Mamirauá e Amanã. Foram avaliados 16 amostras no total, provenientes de dois Acordos de Pesca diferentes (AP1 e AP2). Os microrganismos analisados foram Mesófilos, Staphylococcus aureus, Coliformes Totais e Escherichia coli. As amostras dos dois Acordos de Pesca tiveram presença para todas as bactérias e grupos de bactérias analisados, com valores mais elevados para o AP1. Tendo assim a partir desses resultados a necessidade de um controle maior das condições higiênico-sanitária no fluxograma de beneficiamento dos locais estudados.

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O pirarucu (Arapaima gigas) é um peixe carnívoro da Amazônia e é considerado um dos peixes mais importantes da região. Ele é manejado de forma sustentável por Acordos de Pesca da Reserva de Desenvolvimento sustentável Mamirauá. Dados microbiológicos são necessários para verificar a qualidade higiênico-sanitária dos peixes manejados nessa região. Devido a essa importância o presente trabalho teve como objetivo avaliar a qualidade microbiológica do pirarucu manejado nas Reservas de Desenvolvimento Sustentável Mamirauá e Amanã. Foram avaliados 16 amostras no total, provenientes de dois Acordos de Pesca diferentes (AP1 e AP2). Os microrganismos analisados foram Mesófilos, Staphylococcus aureus, Coliformes Totais e Escherichia coli. As amostras dos dois Acordos de Pesca tiveram presença para todas as bactérias e grupos de bactérias analisados, com valores mais elevados para o AP1. Tendo assim a partir desses resultados a necessidade de um controle maior das condições higiênico-sanitária no fluxograma de beneficiamento dos locais estudados.(AU)

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BACKGROUND: Arapaima gigas (Schinz, 1822) is the largest freshwater scaled fish in the world, and an emerging species for tropical aquaculture development. Conservation of the species, and the expansion of aquaculture requires the development of genetic tools to study polymorphism, differentiation, and stock structure. This study aimed to investigate genomic polymorphism through ddRAD sequencing, in order to identify a panel of single nucleotide polymorphisms (SNPs) and to simultaneously assess genetic diversity and structure in wild (from rivers Amazon, Solimões, Tocantins and Araguaia) and captive populations. RESULTS: Compared to many other teleosts, the degree of polymorphism in A. gigas was low with only 2.3% of identified RAD-tags (135 bases long) containing SNPs. A panel of 393 informative SNPs was identified and screened across the five populations. Higher genetic diversity indices (number of polymorphic loci and private alleles, Shannon's Index and HO) were found in populations from the Amazon and Solimões, intermediate levels in Tocantins and Captive, and very low levels in the Araguaia population. These results likely reflect larger population sizes from less urbanized environments in the Amazon basin compared to Araguaia. Populations were significantly differentiated with pairwise FST values ranging from 0.086 (Amazon × Solimões) to 0.556 (Amazon × Araguaia). Mean pairwise relatedness among individuals was significant in all populations (P < 0.01), reflecting a degree of inbreeding possibly due to severe depletion of natural stocks, the species sedentary behaviour and possible sampling biases. Although Mantel test was not significant (P = 0.104; R2 = 0.65), Bayesian analysis in STRUCTURE and discriminant analysis of principal components (DAPC) showed populations of Amazon and Solimões to be genetically differentiated from Araguaia, with Tocantins comprising individuals from both identified stocks. CONCLUSIONS: This relatively rapid genotyping by sequencing approach proved to be successful in delineating arapaima stocks. The approach and / or SNP panels identified should prove valuable for more detailed genetic studies of arapaima populations, including the elucidation of the genetic status of described discrete morphotypes and aid in delivery of conservation programs to maintain genetic diversity in reservoirs across the Amazon region.

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Dawestrema cycloancistrium is the main ectoparasite causing mortality in fingerlings of pirarucu (Arapaima gigas) in Amazonian aquaculture. Very little is known about the D. cycloancistrium reproductive index and appropriate methods of collecting eggs for investigation. This study aimed to determine the oviposition rate of D. cycloancistrium. To achieve this aim, two egg quantification methods were tested: the estimative method (ME) and the total counting method (MT). Compared with the MT, the ME overestimated the number of eggs counted, which were 2943.5 ± 2840.6 and 1041.5 ± 533 eggs, and the oviposition rate, which was 80.1 ± 58.7 and 31.4 ± 16.4 eggs/parasite/day, for ME and MT, respectively. These results show that for studies quantifying D. cycloancistrium eggs, the total eggs in the sample must be counted, as the estimates made using subsamples are not representative. Using the MT, the oviposition rate for D. cycloancistrium was determined to be 31.4 ± 16.4 eggs per adult parasite per day. The present study demonstrates the egg production capacity of a monogenean species parasite of A. gigas, providing basic biological data for D. cycloancistrium.

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This study aimed to determine the lethal concentration and the structural and ultra-structural effects caused by the formalin exposure on juveniles of Arapaima gigas. Ninety fish (60.1± 2.5g and 20.2±0.9cm) were exposed to 0, 22, 44, 66, 88 and 110mg L-1 in order to determine the lethal concentration (LC50-96h) that was 36.4mg L-1 of formalin. Sublethal effects were evaluated using histopathological analysis on the gills and assessment of behavioral alterations and clinical signs. The LC50 of formalin for 24, 48 and 72h was 88.3, 64.7 and 56.8mg L-1 respectively. Clinical signs and behavioral changes were found: erratic swimming, lethargy, crowding on the water surface, loss of hydrodynamic equilibrium, spasms and agonistic confrontation, which were observed only at 88 and 110mg L-1. The histological alteration index (HAI) showed that 66, 88 and 100mg L-1 presented significant difference (p<0.05) in relation to unexposed fish, indicating that moderate damage to the gills of fish exposed to formalin had occurred. The mean values of alteration (MVA) for 22, 44, 66, 88 and 110mg L-1 were 1.14, 1.29, 1.51, 1.53 and 1.60 respectively, and differences in this index were only observed with 110 mgL-1 of formalin. It is therefore possible to conclude that sublethal concentrations of formalin (22.0mg L-1) did not compromise the health of juveniles of A. gigas. Finally, concentrations greater than to LC50-96h may be carefully used for short-term exposure, since the MVA for all concentrations tested only indicated localized lesions that did not compromise gills functionality of exposed fish.(AU)

O presente estudo teve como objetivo determinar a concentração letal e efeitos estruturais e ultraestruturais causados pela exposição a formalina em juvenis de Arapaima gigas. Noventa peixes (60,1±2,5g e 20,2±0,9cm) foram expostos a 0, 22, 44, 66, 88 e 110mg L-1, para determinar a concentração letal (CL50-96h) de formalina que foi 36,4mg L-1. Os efeitos subletais foram avaliados por análises histopatológicas das brânquias e avaliação das alterações comportamentais e sinais clínicos. A CL50 de formalina para 24, 48 e 72horas foi de 88,3, 64,7 e 56,8; respectivamente. Sinais clínicos e alterações comportamentais encontradas foram: natação errática, letargia, aglomeração de peixes na superfície da água, perda de equilíbrio hidrodinâmico, espasmos e confronto agonísticos, observados apenas nas concentrações de 88 e 110mg L-1. O índice de alteração histológica (IAH) mostrou que as concentrações de 66, 88 e 100mg L-1 apresentaram diferenças significativas (p<0,05) em relação aos controles, indicando a ocorrência de danos moderados nas brânquias dos peixes expostos a formalina. Os valores médios de alteração (VMA) para as concentrações 22, 44, 66, 88 e 110mg L-1 foram 1,14, 1,29, 1,51, 1,53 e 1,60; respectivamente, e as diferenças na composição desse índice foram observados apenas na exposição com 110mg L-1 de formalina. Foi possível concluir que concentrações subletais de formalina (22,0mg L-1) não comprometem a saúde de juvenis de A. gigas. Concentrações de formalina acima da CL50-96h podem ser usadas cuidadosamente para banho de curto tempo, uma vez que o VMA para todas as concentrações testadas indicou apenas lesões localizadas que não comprometem a funcionalidade das brânquias dos peixes expostos.(AU)

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RESUMO

This study aimed to determine the lethal concentration and the structural and ultra-structural effects caused by the formalin exposure on juveniles of Arapaima gigas. Ninety fish (60.1± 2.5g and 20.2±0.9cm) were exposed to 0, 22, 44, 66, 88 and 110mg L-1 in order to determine the lethal concentration (LC50-96h) that was 36.4mg L-1 of formalin. Sublethal effects were evaluated using histopathological analysis on the gills and assessment of behavioral alterations and clinical signs. The LC50 of formalin for 24, 48 and 72h was 88.3, 64.7 and 56.8mg L-1 respectively. Clinical signs and behavioral changes were found: erratic swimming, lethargy, crowding on the water surface, loss of hydrodynamic equilibrium, spasms and agonistic confrontation, which were observed only at 88 and 110mg L-1. The histological alteration index (HAI) showed that 66, 88 and 100mg L-1 presented significant difference (p<0.05) in relation to unexposed fish, indicating that moderate damage to the gills of fish exposed to formalin had occurred. The mean values of alteration (MVA) for 22, 44, 66, 88 and 110mg L-1 were 1.14, 1.29, 1.51, 1.53 and 1.60 respectively, and differences in this index were only observed with 110 mgL-1 of formalin. It is therefore possible to conclude that sublethal concentrations of formalin (22.0mg L-1) did not compromise the health of juveniles of A. gigas. Finally, concentrations greater than to LC50-96h may be carefully used for short-term exposure, since the MVA for all concentrations tested only indicated localized lesions that did not compromise gills functionality of exposed fish.(AU)

O presente estudo teve como objetivo determinar a concentração letal e efeitos estruturais e ultraestruturais causados pela exposição a formalina em juvenis de Arapaima gigas. Noventa peixes (60,1±2,5g e 20,2±0,9cm) foram expostos a 0, 22, 44, 66, 88 e 110mg L-1, para determinar a concentração letal (CL50-96h) de formalina que foi 36,4mg L-1. Os efeitos subletais foram avaliados por análises histopatológicas das brânquias e avaliação das alterações comportamentais e sinais clínicos. A CL50 de formalina para 24, 48 e 72horas foi de 88,3, 64,7 e 56,8; respectivamente. Sinais clínicos e alterações comportamentais encontradas foram: natação errática, letargia, aglomeração de peixes na superfície da água, perda de equilíbrio hidrodinâmico, espasmos e confronto agonísticos, observados apenas nas concentrações de 88 e 110mg L-1. O índice de alteração histológica (IAH) mostrou que as concentrações de 66, 88 e 100mg L-1 apresentaram diferenças significativas (p<0,05) em relação aos controles, indicando a ocorrência de danos moderados nas brânquias dos peixes expostos a formalina. Os valores médios de alteração (VMA) para as concentrações 22, 44, 66, 88 e 110mg L-1 foram 1,14, 1,29, 1,51, 1,53 e 1,60; respectivamente, e as diferenças na composição desse índice foram observados apenas na exposição com 110mg L-1 de formalina. Foi possível concluir que concentrações subletais de formalina (22,0mg L-1) não comprometem a saúde de juvenis de A. gigas. Concentrações de formalina acima da CL50-96h podem ser usadas cuidadosamente para banho de curto tempo, uma vez que o VMA para todas as concentrações testadas indicou apenas lesões localizadas que não comprometem a funcionalidade das brânquias dos peixes expostos.(AU)

Assuntos

RESUMO

The gill structure of the Amazonian fish Arapaima gigas (Cuvier 1829) shows ontogenetic changes during development, particularly due the transition from the aquatic to the obligatory air breathing mode of respiration. However, three main cell types can be found in the gills: mitochondrial rich cells, pavement cells and mucous cells (MCs). The MCs are involved in the secretory pathway. The functions of the secreted molecules include mechanical protection of epithelia, protection against parasites and bacterial infection, and role on ion regulation. In this study, we analysed mucous cell location and mucous cell type, based on pH, during the development of A. gigas. Using samples obtained from the environment, gills were collected and fixed in buffered solution. Histological techniques for the identification of MCs were performed Alcian Blue (AB) and periodic acid-Schiff (PAS). The results showed the presence of PAS+ and AB+ cells in the whole filament in all examined fish. In animals less than 50 g, few MCs were present, and no differences were observed in AB+ and PAS+ cells. In animals weighing close to 500 g, more PAS+ cells than AB+ cells were observed, and in animals that weighed more than 1,000 g, more AB+ cells than PAS+ cells were observed. These observations may be a result of the ontogenetic changes in the gill epithelia, which can change the osmorespiratory compromise in ion regulation functions as well the glycosaminoglycans secreted by PAS cells, which in large animals can play a role in the protection against parasites and bacterial infection.

Assuntos

RESUMO

ABSTRACT: This study aimed to determine the lethal concentration and the structural and ultra-structural effects caused by the formalin exposure on juveniles of Arapaima gigas. Ninety fish (60.1± 2.5g and 20.2±0.9cm) were exposed to 0, 22, 44, 66, 88 and 110mg L-1 in order to determine the lethal concentration (LC50-96h) that was 36.4mg L-1 of formalin. Sublethal effects were evaluated using histopathological analysis on the gills and assessment of behavioral alterations and clinical signs. The LC50 of formalin for 24, 48 and 72h was 88.3, 64.7 and 56.8mg L-1 respectively. Clinical signs and behavioral changes were found: erratic swimming, lethargy, crowding on the water surface, loss of hydrodynamic equilibrium, spasms and agonistic confrontation, which were observed only at 88 and 110mg L-1. The histological alteration index (HAI) showed that 66, 88 and 100mg L-1 presented significant difference (p 0.05) in relation to unexposed fish, indicating that moderate damage to the gills of fish exposed to formalin had occurred. The mean values of alteration (MVA) for 22, 44, 66, 88 and 110mg L-1 were 1.14, 1.29, 1.51, 1.53 and 1.60 respectively, and differences in this index were only observed with 110 mgL-1 of formalin. It is therefore possible to conclude that sublethal concentrations of formalin (22.0mg L-1) did not compromise the health of juveniles of A. gigas. Finally, concentrations greater than to LC50-96h may be carefully used for short-term exposure, since the MVA for all concentrations tested only indicated localized lesions that did not compromise gills functionality of exposed fish.

RESUMO: O presente estudo teve como objetivo determinar a concentração letal e efeitos estruturais e ultraestruturais causados pela exposição a formalina em juvenis de Arapaima gigas. Noventa peixes (60,1±2,5g e 20,2±0,9cm) foram expostos a 0, 22, 44, 66, 88 e 110mg L-1, para determinar a concentração letal (CL50-96h) de formalina que foi 36,4mg L-1. Os efeitos subletais foram avaliados por análises histopatológicas das brânquias e avaliação das alterações comportamentais e sinais clínicos. A CL50 de formalina para 24, 48 e 72horas foi de 88,3, 64,7 e 56,8; respectivamente. Sinais clínicos e alterações comportamentais encontradas foram: natação errática, letargia, aglomeração de peixes na superfície da água, perda de equilíbrio hidrodinâmico, espasmos e confronto agonísticos, observados apenas nas concentrações de 88 e 110mg L-1. O índice de alteração histológica (IAH) mostrou que as concentrações de 66, 88 e 100mg L-1 apresentaram diferenças significativas (p 0,05) em relação aos controles, indicando a ocorrência de danos moderados nas brânquias dos peixes expostos a formalina. Os valores médios de alteração (VMA) para as concentrações 22, 44, 66, 88 e 110mg L-1 foram 1,14, 1,29, 1,51, 1,53 e 1,60; respectivamente, e as diferenças na composição desse índice foram observados apenas na exposição com 110mg L-1 de formalina. Foi possível concluir que concentrações subletais de formalina (22,0mg L-1) não comprometem a saúde de juvenis de A. gigas. Concentrações de formalina acima da CL50-96h podem ser usadas cuidadosamente para banho de curto tempo, uma vez que o VMA para todas as concentrações testadas indicou apenas lesões localizadas que não comprometem a funcionalidade das brânquias dos peixes expostos.

RESUMO

Isopods Cymothoidae are organisms that parasitize several fish species, both marine and freshwater, provoking important physiological alterations and secondary infections. The genus Braga was proposed to harbor three species of parasitic isopods in freshwater fish from South America: B. brasiliensis, B. cichlae and B. nasuta. Posteriorly, other four species were included: B. patagonica, B. amapaensis, B. fluviatilis and B. bachmanni. Regarding the geographical distribution of the genus, there are registers in Brazil, Argentina, Suriname and Paraguay. In this study, 3,625 fingerlings of pirarucu Arapaima gigas were examined from a commercial fish farm in the Amazon region, Pará State, to observe and identify possible parasites. A total of eleven ectoparasitic isopods were carefully removed from the body surface of the hosts and fixed in alcohol 70%. They were processed and identified as Braga nasuta. Parasitological indexes were prevalence of 0.303%, mean intensity of 1.000±0.000 and mean abundance of 0.003±0.055. This is the first report of B. nasuta in pirarucu fingerlings. (AU)

Isópodes Cymothoidae são organismos que parasitam ampla variedade de espécies de peixes, tantomarinhos quanto dulcícolas, provocando importantes alterações fisiológicas e infecções secundárias. O gêneroBraga foi proposto inicialmente para abrigar três espécies de isópodes parasitos de peixes de água doce da Américado Sul: B. brasiliensis, B. cichlae e B. nasuta; posteriormente, outras quatro espécies foram inseridas: B. patagônica, B.amapaensis, B. fluviatilis e B. bachmanni. Em relação à distribuição geográfica das espécies deste gênero, há registrosno Brasil, na Argentina, em Suriname e no Paraguai. Neste estudo, 3.625 alevinos de pirarucu Arapaima gigas deuma piscicultura comercial na região amazônica, Estado do Pará, foram examinados para observar e identificarpossíveis parasitos. Ao total, foram encontrados onze isópodes ectoparasitos, cuidadosamente retirados dasuperfície corporal de hospedeiros e fixados em álcool 70%. Eles foram processados e identificados como Braganasuta. Os índices parasitológicos tiveram prevalência de 0,303%, intensidade media de 1.000±0.000 e abundânciamédia de 0,003±0,055. Este é o primeiro relato de B. nasuta em alevinos de pirarucu.(AU)

Assuntos

RESUMO

Isopods Cymothoidae are organisms that parasitize several fish species, both marine and freshwater, provoking important physiological alterations and secondary infections. The genus Braga was proposed to harbor three species of parasitic isopods in freshwater fish from South America: B. brasiliensis, B. cichlae and B. nasuta. Posteriorly, other four species were included: B. patagonica, B. amapaensis, B. fluviatilis and B. bachmanni. Regarding the geographical distribution of the genus, there are registers in Brazil, Argentina, Suriname and Paraguay. In this study, 3,625 fingerlings of pirarucu Arapaima gigas were examined from a commercial fish farm in the Amazon region, Pará State, to observe and identify possible parasites. A total of eleven ectoparasitic isopods were carefully removed from the body surface of the hosts and fixed in alcohol 70%. They were processed and identified as Braga nasuta. Parasitological indexes were prevalence of 0.303%, mean intensity of 1.000±0.000 and mean abundance of 0.003±0.055. This is the first report of B. nasuta in pirarucu fingerlings.

Isópodes Cymothoidae são organismos que parasitam ampla variedade de espécies de peixes, tanto marinhos quanto dulcícolas, provocando importantes alterações fisiológicas e infecções secundárias. O gênero Braga foi proposto inicialmente para abrigar três espécies de isópodes parasitos de peixes de água doce da América do Sul: B. brasiliensis, B. cichlae e B. nasuta; posteriormente, outras quatro espécies foram inseridas: B. patagônica, B. amapaensis, B. fluviatilis e B. bachmanni. Em relação à distribuição geográfica das espécies deste gênero, há registros no Brasil, na Argentina, em Suriname e no Paraguai. Neste estudo, 3.625 alevinos de pirarucu Arapaima gigas de uma piscicultura comercial na região amazônica, Estado do Pará, foram examinados para observar e identificar possíveis parasitos. Ao total, foram encontrados onze isópodes ectoparasitos, cuidadosamente retirados da superfície corporal de hospedeiros e fixados em álcool 70%. Eles foram processados e identificados como Braga nasuta. Os índices parasitológicos tiveram prevalência de 0,303%, intensidade media de 1.000±0.000 e abundância média de 0,003±0,055. Este é o primeiro relato de B. nasuta em alevinos de pirarucu.

Assuntos