Osteoglossum Bicirrhosum Research Articles

HELMINTHIC ENDOFAUNA OF FOUR SPECIES OF FISH FROM LOWER JARI RIVER, A TRIBUTARY OF THE AMAZON BASIN IN BRAZIL

Studies on parasites of wild fish populations are important for knowledge of biodiversity, since parasites represent a great fraction of the planet's biodiversity. The present study investigated the helminths fauna of Leporinus friderici, Mylossoma duriventre, Hoplerythrinus unitaeniatus and Osteoglossum bicirrhosum collected from the lower Jari River, in the state of Amapá in the eastern Amazon region, Brazil. These fish, which have varying eating habits, were caught using gill nets with different mesh sizes for analysis of helminths, using standard methodologies. The helminths collected from these hosts were: Procamallanus (Spirocamallnus) inopinatus, Guyanema seriei seriei, Contracaecum sp., Eustrongylides sp. (Nematoda), Clinostomum marginatum, Dadaytrema oxycephala, Caballerotrema aruanense, Posthodiplostomum sp. (Digenea), Quadrigyrus nickoli and Neoechinorhynchus sp. (Acanthocephala). Hoplerythrinus unitaeniatus presented the highest prevalence, intensity and mean abundance of C. marginatum, while M. duriventre was the host with lowest level of this parasite. The greatest diversity was of Contracaecum sp., sole helminth found in all species of fish studied. The presence of larvae of endoparasites indicates that these fish are intermediate hosts in the Jari River basin.

Ichthyofauna from floodplain lakes of Reserva de Desenvolvimento Sustentável Piagaçu-Purus (RDS-PP), lower rio Purus

Abstract: The ichthyofauna of the rio Purus has been little investigated, especially in its lower portion, characterized by diverse aquatic environments, especially in flooded areas. We inventoried the ichthyofauna of floodplain lakes with different management efforts in Reserva de Desenvolvimento Sustentável Piagaçu-Purus (RDS-PP), which represent important resource for commercial fishing in North region, in the first illustrated inventory of the fish fauna from lower rio Purus. We surveyed 20 lakes, classified as open access (eight lakes) and protected (12 lakes) during 2009 low water levels. A total of 2,299 individuals were collected, represented by seven orders, 25 families and 74 species. Characiformes was the most representative order in number of species and families, followed by Siluriformes, Cichliformes, Gymnotiformes, Clupeiformes, and Osteoglossiformes. Most abundant and frequent species were Pygocentrus nattereri, Triportheus angulatus, Serrasalmus sp. "2n=58", Pterygoplichthys gibbiceps, and Osteoglossum bicirrhosum. Protected lakes presented higher species richness compared to open access lakes. Similarly, protected lakes possessed 26 species occurring exclusively, with emphasis on Colossoma macropomum, an important species for fisheries due to its commercial importance. We added 44 new records of fish species for the lower rio Purus. Our results indicate the potential efficiency of zoning systems of open access and protected lakes established by local population and ruled by RDS-PP for fisheries management. Therefore, we strongly suggest its maintenance for conservation of ichthyofauna of floodplain lakes of lower rio Purus.

Mice on menu: opportunistic feeding behaviour of the Amazonian silver arowana Osteoglossum bicirrhosum.

Two silver arowana, Osteoglossum bicirrhosum, one male (49.5 cm standard length, LS ) and one female (52.5 cm LS ) that had fed on small-eared colilargo or small-eared pygmy rice rat Oligoryzomys microtis, were sampled during the rising water period in the Brazilian Amazon. The identified prey were 6 and 8 cm long and occupied the entire stomachs of both individuals. This opportunistic feeding behaviour appears to be a strategy for this fish to acquire nutrients during times when its usual aquatic prey is dispersed throughout the flooded forest.

Mice on menu: opportunistic feeding behaviour of the Amazonian silver arowana Osteoglossum bicirrhosum.

Two silver arowana, Osteoglossum bicirrhosum, one male (49.5 cm standard length, LS ) and one female (52.5 cm LS ) that had fed on small-eared colilargo or small-eared pygmy rice rat Oligoryzomys microtis, were sampled during the rising water period in the Brazilian Amazon. The identified prey were 6 and 8 cm long and occupied the entire stomachs of both individuals. This opportunistic feeding behaviour appears to be a strategy for this fish to acquire nutrients during times when its usual aquatic prey is dispersed throughout the flooded forest. This article is protected by copyright. All rights reserved.

Evaluación de la eficiencia de tres modelos de incubadora con diferentes flujos en el desarrollo larval de Osteoglossum bicirrhosum (arawana plateada)

El objetivo de este estudio fue evaluar la eficiencia de tres modelos de incubadora con diferente flujo para el desarrollo larval de Osteoglossum bicirrhosum (arawana plateada), desde el estadio dos al estadio cinco. Se trabajó con 60 larvas y se distribuyeron en grupos de 20 por cada modelo de incubadora: MI1: flujo circular; MI2: flujo ascendente; MI3: sin flujo. Se determinó el diámetro corporal (DC), diámetro del saco vitelino (DSV), adquisición natatoria (AN) y mortalidad durante 30 días de incubación. El DC final para MI1 fue de 33.77 mm comparado con 33.16 mm para MI2 y 19.92 mm para MI3. El DSV inicial de 12.02 mm en MI1 disminuyó en MI2 (11.64 mm) y aumentó a 12.11 mm en MI3. La adquisición natatoria se presentó en todas las larvas de MI1 y MI2, pero solo en el 10% de MI3. Asimismo, la mortalidad fue de 1, 10 y 20 larvas para MI1, MI2 y MI3, respectivamente.

Small size today, aquarium dumping tomorrow: sales of juvenile non-native large fish as an important threat in Brazil

ABSTRACT Informal sales of large-bodied non-native aquarium fishes (known as “tankbusters”) is increasing among Brazilian hobbyists. In this study, we surveyed this non-regulated trade on Facebook® from May 2012 to September 2016, systematically collecting information about the fishes available for trading: species, family, common/scientific names, native range, juvenile length, behavior, number of specimens available in five geographical regions from Brazil. We also assessed the invasion risk of the most frequently sold species using the Fish Invasiveness Screening Test (FIST). We found 93 taxa belonging to 35 families. Cichlidae was the dominant family, and most species were native to South America. All species are sold at very small sizes (< 10.0 cm), and most display aggressive behavior. The hybrid Amphilophus trimaculatus × Amphilophus citrinellus, Astronotus ocellatus, Uaru amphiacanthoides, Osteoglossum bicirrhosum, Cichla piquiti, Pangasianodon hypophthalmus, Datnioides microlepis and Cichla kelberi were the main species available. The southeast region showed the greatest trading activity. Based on biological traits, the FIST indicated that Arapaima gigas, C. kelberi and C. temensis are high-risk species in terms of biological invasions via aquarium dumping. We suggest management strategies such as trade regulations, monitoring, euthanasia and educational programs to prevent further introductions via aquarium dumping.

Morphofunctional features of visceral apparatus of silver arawana Osteoglossum bicirrhosum (Osteoglossidae)

The structure of some muscles—previously undescribed ligaments and aponeurotic structures of the visceral apparatus—of silver arawana Osteoglossum bicirrhosum has been studied in detail. A comparative analysis of the obtained results of anatomization and literature data is carried out. The peculiarities of the functioning of the visceral apparatus of silver arawana in the process of feeding are considered. New features of similarity in the structure of muscles of the visceral apparatus of Osteoglossidae and Salmonidae (by the example of salmon Salmo salar), which can provide a basis for confirming previously detected homologous features in the feeding stages of these two primitive groups of fish, are described.

A diní­¢mica sazonal das pescarias de pequena escala na Amazônia é definida pelo pulso hidrológico

O presente estudo analisou a diní­¢mica de uma pescaria de pequena escala na Amazônia em associação com o ciclo hidrológico. Dados de desembarque pesqueiro foram coletados diariamente no perí­­odo de fevereiro/2007 a janeiro/2008 no Porto Panairzinha em Manacapuru, Amazonas í Brasil (3°18’33”S e 60°33’21”W). Os resultados mostraram que a frota atuante no Lago Grande é composta por canoas motorizadas e barcos de pesca, sendo o número de canoas superior ao de barcos. A média do pescado desembarcado foi de 274,15 ton.ano-1, ocorrendo menor produção nos perí­­odos de enchente/cheia e maior na vazante/seca. As principais espécies desembarcadas foram: Colossoma macropomum (tambaqui = 17,8%), Cichla monoculus (tucunaré = 15,5%), Prochilodus nigricans (curimatã = 12,2%), Astronotus ocellatus (acará-açu = 8,7%) e Osteoglossum bicirrhosum (aruanã = 8,4%), predominando a malhadeira (97%) nessas capturas. Foi observado que a sazonalidade do Rio Solimões influi diretamente nas pescarias e na disponibilidade do pescado. Nesse sentido, decisões envolvendo o manejo pesqueiro nessa região devem estabelecer medidas que assegurem a sustentabilidade da pesca local, considerando como essencial a relação entre o peixe, o ambiente e os aspectos socioeconômicos das pescarias de pequena escala.

Atividade pesqueira dos índios Mura no Lago Ayapuá, Baixo Rio Purus, Amazonas, Brasil

A pesca artesanal apresenta grande importância para as comunidades indígenas Amazônicas, como meio de subsistência e pelas marcas culturais e de tradição dessas comunidades. Neste estudo analisamos a pesca desenvolvida em quatro comunidades indígenas da etnia Mura da Terra Indígena Lago Ayapuá (TI-LA) no baixo rio Purus. Caracterizou-se a pesca quanto à composição e importância das espécies em peso e número de indivíduos, estrutura e tamanho dos indivíduos capturados, e peso total das capturas, entre outubro e dezembro de 2008. As espécies mais comercializadas foram o aruanã (Osteoglossum bicirrhosum), pescada (Plagioscion squamosissimus), as “feras” (dourada, Brachyplatystoma rousseauxii e filhote Brachyplatystoma filamentosum) e o tucunaré Cichla monoculus. Já as espécies mais consumidas foram aruanã, tucunaré, piranha-caju (Pygocentrus nattereri) e acará-açu (Astronotus crassipinni). Espécies como tucunaré e pescada apresentam tamanhos de captura dentro dos padrões permitidos pela legislação. No entanto, o acará-açu, aruanã, tambaqui (Colossoma macropomum), surubim (Pseudoplatystoma punctifer), caparari (Pseudoplatystoma tigrinum), filhote e dourada não apresentam o mesmo padrão legal. A maior parte da produção (87%) foi destinada para a comercialização com barcos atravessadores. Medidas mitigatórias e preventivas são propostas para garantir a permanência dos estoques pesqueiros e consequentemente a sustentabilidade da pesca e a manutenção da população ribeirinha local.

Diversification of Hox Gene Clusters in Osteoglossomorph Fish in Comparison to Other Teleosts and the Spotted Gar Outgroup.

An ancient genome duplication (TGD or 3R) occurred in teleost fish after divergence from the lineage leading to gar. This genome duplication is shared by the three extant teleost lineages: Osteoglossomorpha (bony-tongues), Elopomorpha (eels and tarpons), and Clupeocephala (a large clade including salmon, carp, medaka, zebrafish, cichlids, pufferfish, stickleback, and ∼26,000 other species). After TGD, different clupeocephalan species retained different gene duplicates; this is seen clearly in Hox gene clusters but extends to all genes. Since divergent resolution of TGD paralogs is a potential driving force for speciation, it is possible this contributed to diversification of this clade. The extent to which divergent resolution of TGD paralogs occurred within Osteoglossomorpha has not been investigated in detail, and Hox cluster organization has been reported for just two species: Pantodon buchholzi (Pantodontidae) and Scleropages formosus (Osteoglossidae). We applied survey-scale genome sequencing and de novo assembly to three further osteoglossomorph taxa: Osteoglossum bicirrhosum (Osteoglossidae), Chitala ornata (Notopteridae), and Gnathonemus petersii (Mormyridae). We find that each retained more Hox genes than clupeocephalan taxa (excluding those that underwent additional genome duplication), but fewer than eels. Several Hox genes are missing in all teleosts, including duplicates of two Hox genes present in the slow evolving pre-TGD genome of the spotted gar. We find divergent resolution through individual gene losses, and whole cluster losses have been rampant across osteoglossomorphs, despite their extant species paucity. We suggest that reciprocal gene loss following TGD was probably insufficient to drive the exceptional diversification of teleosts.

Transboundary fisheries management in the Amazon: Assessing current policies for the management of the ornamental silver arawana (Osteoglossum bicirrhosum)

The management and governance of shared stocks have long been identified as a challenge to achieve long-term sustainability in fisheries. This is the situation of fisheries in the Amazon basin, a region shared by nine countries. This paper provides an overview of the social-ecological outcomes and management implications of sharing fish stocks among countries with different public policies, taking the valuable Amazonian ornamental silver arawana (Osteoglossum bicirrhosum) trade as a case study. Specifically, it (i) presents and discusses the policies of Colombia, Peru and Brazil for the silver arawana fishery, and how these are conducive for the successful management of this shared transboundary fishery; and (ii) analyzes the market for the ornamental silver arawana and how it affects the ability to sustainably manage the fishery. The interplay between the multiple environmental, economic and social dimensions involved in the ornamental silver arawana fishery affects the sustainability of this species even in Brazil, where this fishing is forbidden but still illegally caught by Colombians and Peruvians. Among the factors that make fisheries policies inefficient in this region are: (i) incongruent policies between the countries and institutions with low organizational capacity to accomplish the established policies; (ii) environmental heterogeneity of Amazonian aquatic systems, which requires local and adaptive measures; and (iii) complex socio-economic relationships in the live-fish trade business. Legally binding efforts to reduce problems derived from shared fish stocks are an urgent need and should be addressed by the multilateral organizations created for the Amazonian sustainable development.

Anatomical, histochemical and immunohistochemical characterisation of the cardiac outflow tract of the silver arowana, Osteoglossum bicirrhosum (Teleostei: Osteoglossiformes)

The cardiac outflow tract of chondrichthyans and actinopterygians is composed of a myocardial conus arteriosus and a non-myocardial bulbus arteriosus. In teleosts, the conus has been subjected to a reduction in size over the evolution in conjunction with the further development of the bulbus. Most studies on the outflow tract of the teleost heart refer to species of modern groups and are mainly devoted to the bulbus. Knowledge on the outflow tract of species belonging to early teleost groups is scarce. The aim here was to characterise the structure of the cardiac outflow tract of the silver arowana, a representative of the ancient teleost clade of the Osteoglossomorpha. The material consisted of hearts from six juvenile animals. The cardiac outflow tract of the silver arowana is composed of a conus, which supports two conal valves, and a bulbus. Both components are lined externally by the epicardium and internally by the endocardium. The conus is immunoreactive to antibodies against myosin heavy chains and is composed of compact myocardium, thus contrasting with the ventricle, which has exclusively trabeculated myocardium. The bulbus is immunoreactive to antibodies against smooth muscle α-actin and mainly consists of elastic fibres and smooth muscle cells, both arranged in three layers, outer, middle and inner. The most remarkable feature of the bulbus is the presence of two prominent longitudinal ridges, dorsal and ventral, at the luminal side, which serve to anchor the commissures of the conal valves. This arrangement has not been described so far in any fish species. Pigment cells, presumably of neural crest origin, are present in the subepicardium of the bulbus and anterior part of the ventricle.

In vitro effects of increased temperature and decreased pH on blood oxygen affinity of 10 fish species of the Amazon.

Blood-O2 affinities (P50 ) were measured over a physiologically relevant pH range at 31 (highest temperature average of Rio Negro over the last 8 years), 33 and 35° C for 10 species of the Rio Negro, aiming to test the acute effects of temperature foreseen by the IPCC (Intergovernmental Panel on Climate Change) for coming years. The animals were collected during an expedition to the Anavilhanas Islands of the Rio Negro, 110 km upstream from Manaus (2° 23' 41″ S; 60° 55' 14″ W). Hoplias malabaricus showed higher blood-O2 sensitivity to pH changes (Bohr effect, Φ = Δlog10 P50 ΔpH(-1) ) at both 31° C (Φ = -0·44) and 35° C (Φ = -0·26) compared to Osteoglossum bicirrhosum (Φ = -0·54 at 31° C and Φ = -0·58 at 35° C), but lower P50 under most conditions, and a greater sensitivity of P50 to temperature. Two out of the 10 analysed species had significant increases of P50 (lower blood-O2 affinity) at the highest temperature throughout the pH range tested. For all other species, a minor increase of P50 over the assay-tested temperatures was observed, although all presented a normal Bohr effect. Overall, a diversity of intensities of pH and temperature effects on blood-O2 affinities was observed, which seems to be connected to the biological characteristics of the analysed species. Thermal disturbances in their habitats, likely to occur due to the global warming, would impair blood-O2 binding and unloading in some of the analysed fish species. Copyright © 2016 John Wiley & Sons, Ltd.

Growth, survival and the histology of the digestive tract of juvenile Osteoglossum bicirrhosum (Cuvier, 1829) fed three diets containing different protein and lipid levels

The influence of three commercial diets with different protein and lipid contents (40 : 14, 45 : 8, 48 : 8 protein : lipid – P : L, in % dry weight of diet) on growth performance, survival and the histology of the liver and intestine was analysed in early juveniles of silver arowana, Osteoglossum bicirrhosum, reared in captivity. Individuals (initial wet weight–Wi = 1.07 ± 0.04 g; total length–TL = 6.0 ± 0.17 cm) were raised in triplicate (n = 12 fish per tank) at 26.2 ± 0.1°C and fed one of three commercial diets over 60 days. At the end of the trial, survival (90.5 ± 3.3%) and condition factor (0.5 ± 0.02) were not affected by dietary treatments, whereas specific growth rate, TL and W gain were lower in animals fed the 40P : 14L diet. Histological analysis revealed a larger accumulation of lipid droplets in the intestines of the group supplied with the 40P : 14L diet, as well as a larger surface of hepatic lipid vacuoles compared to the other treatments, although no signs of steatosis were observed. Juveniles fed the 48P : 8L diet displayed the lowest liver lipid accumulation; however, a protein content higher than 45% did not improve growth performance. The intestine and liver lipid accumulation of individuals fed the 45P : 8L diet might indicate a more balanced lipidic metabolism. Intestine and liver histologies proved to be useful markers to identify the nutritional condition in juveniles of O. bicirrhosum, even when differences in nutritional composition were subtle (i.e. protein variation of 3%).

Variations in reproductive strategy of the silver Arowana, Osteoglossum bicirrhosum Cuvier, 1829 from four sub-basins of the Peruvian Amazon

Variations in reproductive strategy of the silver Arowana, <i>Osteoglossum bicirrhosum</i> Cuvier, 1829 from four sub-basins of the Peruvian Amazon

Bioelectric fields of the African marbled lungfish Protopterus aethiopicus (Sarcopterygii: Protopteridae), African (Heterotis niloticus) and South American silver (Osteoglossum bicirrhosum) arowanas (Actinopterygii: Osteoglossidae): Primitive electrogenesis?

Sporadic weak electric discharges were recorded from the African marbled lungfish (Protopterus aethiopicus), African arowana (Heterotis niloticus) and South American silver arowana (Osteoglossum bicirrhosum). In all species, the discharges were registered from a pair of freely swimming individuals left for several hours in an experimental tank, or evoked by tactile stimulation in the lungfish and the African arowana. Maximum amplitudes of recoded pulses ranging from 1.5 mV in Osteoglossum to 10 mV in Protopterus and Heterotis, as well as the coordinated discharge patterns, allow us to suggest the existence of anatomically and physiologically specialized electrogenic tissue in these species. The phylogenetic and evolutionary significance of primitive electrogenesis in the lobe-finned and bony-tongue fishes is discussed.

Factors determining the structure of fish assemblages in an Amazonian river near to oil and gas exploration areas in the Amazon basin (Brazil): establishing the baseline for environmental evaluation

Determining the significance of biotic and abiotic factors in the structuring of fish assemblages in freshwater environments is an important question in ecology, particularly in view of environmental changes caused by man. In this paper we sought to identify the factors responsible for the composition and abundance of fish species collected with gill nets in six locations near ports in forest clearance areas opened up for oil and natural gas exploration (Petrobras Pedro Moura Base) in the Urucu River, during drought and flood cycles. In all, 923 individuals from 23 families and 82 species were collected, totalling a biomass of 182,244 g. The most abundant species during the flood season were Bryconops alburnoides (Kner, 1858) and Dianema urostriatum (Miranda Ribeiro, 1912); in the drought season, the predominant species were Osteoglossum bicirrhosum (Cuvier, 1829) and Serrasalmus rhombeus (Linnaeus, 1766). The species with the greatest biomass during the flood season were Pellona castelnaeana (Valenciennes, 1847), S. rhombeus and Pellona flavipinis (Valenciennes, 1847). During the drought season, the predominant species was O. bicirrhosum. When both periods were analysed together, electrical conductivity, water transparency and dissolved oxygen were the most important factors. The species Hemisorubim platyrhynchos (Valenciennes, 1840), O. bicirrhosum, Chaetobranchus flavenscens Heckel, 1840, Geophagus proximus (Castelnau, 1855) were strongly related to high values of conductivity, pH and water current velocity during the drought season, as well as Serrasalmus altispinis Merckx, Jegu & Santos, 2000, Triportheus albus Cope, 1872, Triportheus angulatus (Spix & Agassiz, 1829) and Brycon melanopterus (Cope, 1872) that were associated with less depth and width in the drought season whereas P. castelnaeana, D. urostriatum, Rhytiodus argenteofuscus Kner, 1858 and Sorubim lima (Bloch & Schneider, 1801) were mainly associated with high transparency and dissolved oxygen during the flood season.

Composição nutricional de dieta enteral artesanal a partir de alimentos convencionais do Município de Coari, Estado do Amazonas, Brasil

El objetivo de este estudio fue el de determinar la composicion nutricional de una dieta artesanal de bajo costo, elaborada con alimentos convencionales del Municipio de Coari, Estado de Amazonas, Brasil, se utilizo arawana (Osteoglossum bicirrhosum), yuca (Manihot esculenta Crantz), pupuna (Bactris gasipaes) y caruru (Amaranthus deflexus L.), para obtener las harinas y el concentrado proteico, luego de la elaboracion de una formula, idealizada por analisis de ensayo y error, se calcularon las proporciones de cada alimento con relacion a la composicion de los constituyentes quimicos recomendados para la dieta enteral. Fue establecida la dilucion y se realizaron los analisis de estabilidad, fluidez, goteo gravitacional, composicion centesimal, composicion de minerales, analisis microbiologico y viabilidad financiera. La formula presento un valor proteico de 13,18 g, 1,99 g de lipidos, 3,64 g de cenizas, 73,03 g carbohidratos y 5,16 g de fibra por cada 100 g respectivamente. En relacion al tenor de minerales, se encontraron 52,48 mg de sodio, 24,32 mg de calcio, 64,04 mg de magnesio, 1,46 mg de manganeso, 5,95 mg de zinc, 2,22 µg de cobre y 0,46 mg de hierro por 100 g de la muestra, respectivamente. Con dilucion 1 g: 1,5 mL de agua, la dieta presento densidad calorica de 1,51 kcal/mL y fluidez adecuada para administracion gravitacional, con goteo medio de 68 gotas por minuto. La formula presento estandares microbiologicos adecuados a la legislacion vigente y costo aparente de R$ 0,56 por 100 g. La dieta artesanal presenta fluidez adecuada, facil preparo y bajo costo, caracterizandose como una dieta especializada, debido a la composicion nutricional, que puede ser clasificada como hipercalorica, normoproteica, hiperglucidica, hipolipidica, y con fibras

Productivity and Reproductive Characteristics of Silver Arowana Osteoglossum bicirrhosum (Osteoglossiformes: Osteoglossidae) at Grande lake, Putumayo basin, Peru

Due to the importance of ornamental fishing of silver arowana, as well as, Lago Grande lake as one of the main areas for capturing baby arowanas in Peru, the present study aimed to evaluate the productivity and the biological-reproductive characteristics of the species in the lake, which is located in the lower basin of the Putumayo River and represents an area preferred by fishermen because the important populations of silver arowana inhabiting it. Analysis of population density, biometrics, sexual maturity, spawning, fecundity, sex ratio, water level of the lake and production of baby arowana were made. The study was developed between March and July of 2012 and to implement the activities of the study was important the participation of the Association of Fishermen “Fronteras Vivas”. In general, the population density extrapolated to the lake area was 1.29 fish/ha. Of these, the density of progenitors in the lake was 1.19 fish/ha. Also, male animals had total length, standard length and total weight higher than females and it was observed that the spawning period occurred in synchronization with the start of the growing of the hydrological regime. The average number of oocytes produced by females of silver arowana in the study area was 201 and the sex ratio was equilibrated. Furthermore, the study shows the capacity of production of the lake. In order to this the water lever influenced in the production of baby arowanas. It is important to continue studying the species for regulate the fishing and recover populations. Keywords: baby arowana; production; ornamental trade; length of first sexual maturity; fishing. Normal 0 21 false false false PT-BR X-NONE X-NONE

Evidence of multiple paternity and cooperative parental care in the so called monogamous silver arowana Osteoglossum bicirrhosum (Osteoglossiformes: Osteoglossidae)

Monogamy is rare in fishes and is usually associated with elaborate parental care. When parental care is present in fishes, it is usually the male that is responsible, and it is believed that there is a relationship between the high energetic investment and the certainty of paternity (except in the case of sneaker males). Osteoglossum bicirrhosum is considered a monogamous fish, and has particular behavioral traits that permit the study of mating systems and parental care, such as male mouthbrooding. We investigated the genetic relationships of males with the broods found in their oral cavities in Osteoglossum samples collected in a natural environment in the lower Purus river basin, Amazonas, Brazil. Fourteen broods were analyzed for parentage (268 young and 14 adult males) using eight microsatellite loci. The results indicate that eleven broods show a monogamous system. In one brood, however, approximately 50% of the young were genetically compatible with being offspring of another male, and in another two broods, none of the subsampled young were compatible with the genotypes of the brooding male. The result of this first brood may be explained by the extra-parental contribution of a sneaker male, whereas cooperative parental care may explain the result in the other two broods.