Pygocentrus Nattereri Research Articles

Sazonalidade da fauna de metazoários de Pygocentrus nattereri (Kner, 1858) no lago Piranha (Amazonas, Brasil) e a avaliação de seu potencial como indicadora da saúde do ambiente

Foi estudada a fauna de metazoários parasitos de Pygocentrus nattereri capturadas no lago Piranha, durante as fases do ciclo hidrológico do ano de 2007. Foi verificada a relação entre o fator de condição e a ocorrência de parasitos, e também a viabilidade da utilização da fauna parasitária de P. nattereri como bioindicadora da saúde do ambiente. Foram coletados monogenóideos das espécies Amphithecium microphalum, Amphitecium brachycirrum, Amphitecium calycinum, Amphithecium catalaoensis, Amphithecium junki, Pithanothecium amazonensis e Rhinoxenus piranhus, o nematóide Procamallanus inopinatus, copépodos da espécie Miracetyma sp. e o isópoda Anphira branchialis. Não houve correlação significativa entre a ocorrência dos parasitos com o fator de condição dos peixes. Houve variações significativas entre os índices parasitários nos diferentes períodos do ciclo hidrológico e P. nattereri satisfez os requisitos descritos na literatura para selecionar um peixe hospedeiro e sua parasitofauna como bioindicadora.

Risk and benefit assessment of alien fish species of the aquaculture and aquarium trade into India

AbstractThere has been an increasing demand for alien fish species in India. However, environmental, socioeconomic and biodiversity issues are important considerations when regulating the unauthorized culture and spread of alien species. Information collected in the present review revealed the presence of over 300 alien species imported intentionally or illegally; 291 ornamental species, 31 aquaculture species and two larvicidal fishes. Field data demonstrated the widespread occurrence of some of the world’s worst invasive species, for example, Cyprinus carpio, Oreochromis niloticus, Aristichthys nobilis, Pygocentrus nattereri and Pterygoplichthys spp., in inland waters; other species are emerging as a threat to aquatic biodiversity. The benefits and risks of alien species were analysed and the impact was quantified using a simple developed ‘Fish Invasiveness Screening Test’ (FIST). Our information suggests that alien species, despite possessing some attractive culture characteristics, generally reduce the availability of local species and establish in natural water bodies becoming invasive and consequently adversely affecting fish biodiversity and aquatic ecosystems. In light of the adverse ecological impacts of alien species, we developed strategic regulations and quarantine procedures and advised aquaculturists to strictly follow them to contain potential and plausible menaces.

Expanded description of Dolops bidentata (Bouvier, 1899) (Branchiura: Argulidae) based on specimens collected on Pygocentrus nattereri Kner, 1858 (Characiformes) from Poconé Wetland, MT, Brazil

The current information on the branchiuran Dolops bidentata, a species described more one hundred years ago, is valid but incomplete; hence, an expanded description is given herein. Additional morphological information was obtained by light and scanning electron microscopy from specimens collected on Pygocentrus nattereri from the Poconé Wetland, MT, Brazil. Description of the appendages and other structures such as respiratory area, mouth, details and ornamentation of antennules and maxillae are provided for the first time.

Reproductive strategies of Red-bellied Piranha (Pygocentrus nattereri Kner, 1858) in the white waters of the Mamirauá flooded forest, central Brazilian Amazon

Despite being an important member of neotropical fish assemblages, as well as a species with an unenviable reputation, little is known about the reproductive ecology of Red-bellied Piranha, Pygocentrus nattereri, in the wild. We tracked the reproductive activity of piranhas in the flooded forests of Mamiraua Reserve, Central Brazilian Amazon, for 2 years, in an investigation that included over 3,000 individual fish. Contrary to expectation piranhas had not one, but rather two annual reproductive seasons, tuned to water level fluctuation and the flooding pulse. Females were found to have up to 30,000 oocytes, little more than one third of which were mature and available for spawning in a single batch. Sexual maturation (of both males and females) occurred at around 160 mm. At this point sexually active individuals (of both sexes) became dark and lost most of their red coloration. Ontogenetic changes in habitat selection were strongly associated with the spawning behavior of mature adults. We also found that flooded marginal vegetation and marginal grasses inside lakes were the preferred spawning areas. In contrast, non-reproductive individuals were found in open water and under floating meadows.

Brevimulticaecum sp. (Nematoda: Heterocheilidae) larvae parasitic in freshwater fish in the Pantanal wetland, Brazil

During the study of metazoan parasites of freshwater fish in the Pantanal wetland (state of Mato Grosso do Sul, Brazil), third-stage larvae of Brevimulticaecum sp. were collected from the abdominal cavity, liver parenchyma, mesentery, skeletal muscles and stomach wall of the following species: Gymnotus inaequilabiatus, Hemisorubim platyrhynchos, Hoplias aff. malabaricus, Myleus levis, Pseudoplatystoma corruscans, Pygocentrus nattereri, Serrasalmus marginatus and Sorubim lima. The larvae exhibited the main characteristics of the genus Brevimulticaecum, such as short ventricular appendices and the position of excretory pore and excretory nucleus. This is the first report and description of larval specimens of Brevimulticaecum parasitic in these hosts, which are fish species distributed throughout South America.

Straminipilous organisms growing on herbivorous pirapitinga (Piaractus brachypomus) and carnivorous piranha (Pygocentrus nattereri) from Poland

We investigated the growth of straminipilous organisms on the skin, muscles and liver of herbivorous pirapitinga (Piaractus brachypomus) and carnivorous piranha (Pygocentrus nattereri) in water of three different eutrophication levels. Sixteen straminipilous organism species were found growing on the investigated body parts of both species of fish used as baits. The higher number of species was found on the baits of carnivorous species (15) when compared with the ones from the herbivorous pirapitinga (10 species). The highest number of straminipilous organisms species developed on the skin of both species of fish. The highest number of species of straminipilous organisms was observed growing in the water of the BiaBa river (middle eutrophication), while the lowest number occurred in the baits of vessels with water from the Dojlidy pond (low eutrophication).

Distribution of External Taste Buds in Walking Catfish (Clarias batrachus) and Piranha (Serrasalmus nattereri)

Raji, A.R. and Norozi, E. 2010. Distribution of external taste buds in walking catfish (Clarias batrachus) and piranha (Serrasalmus nattereri). J. Appl. Anim. Res., 37: 49–52. To determine the distribution of external taste buds (TB), 3 specimen each of the two species of aquarium fishes: Walking catfish (Claris batrachus) and Piranha (Serrasalmus nattereri), were studied. In walking catfish TB were in the highest frequencies in lips, barbels, pelvic and dorsal fins but in the piranha the TB was located only in lip epithelium. The mucous cells were observed together with TB in skin and barbels of both species.

Patterns of energy allocation to reproduction in three Amazonian fish species

The study considered the influence of the hydrological cycle and gonadal development on the accumulation and use of energy in three fish species from an Amazonian flooded area. Fishes were sampled over a 24 hour period at monthly intervals between July 2004 and June 2005 using gillnets of different mesh sizes. Body cavity fat and gonadosomatic indices were determined, as well as energy content of gonads and muscles. Amongst the studied species, different means of energy allocation for reproduction were found: Acestrorhynchus falcirostris allocate energy from body cavity fat to its gonads; Pygocentrus nattereri uses mainly energy accumulated in the muscles for the process of gonadal maturation; and Hoplosternum littorale uses energy accumulated in their muscles and body cavity fat for reproductive processes. It is quite clear that the flood pulse regulates the gain and use of the energy reserves in fishes from the Amazonian floodplain.

Aspectos ecológicos de endoparasitos de piranha vermelha (Pygocentrus nattereri, Kner, 1860) proveniente do rio Cuiabá

ABSTRACT This study evaluated the infrapopulations of parasites in red piranha (Pygocentrus nattereri) from the Cuiaba river, Mato Grosso, Brazil. One hundred sixty-four specimens of red piranha were captured and examined in the period from October to December, 2007 in Barao de Melgaco, Mato Grosso, Brazil. The parasitism was reviewed by data of prevalence, localization, mean intensity of infection, and abundance for each group of parasite found. In the examined fishes, nematodes (Eustrongylides spp., Contracaecum spp,. and Procamallanus spp.) and pentastomids were found. Among the examined fishes, 141 (86%) presented parasitism by at least one species of parasite; from those, 23 (14%) by nematodes identified as Eustrongylides spp., 106 (64.6%) b y Contracaecum spp., 55 (33.5%) by Procamallanus spp., and 90 (54.9%) by pentastomids. About the localization of the parasites, from the 23 fishes positive to the infection by Eustrongylides spp., 19 (82.6%) presented larvae in the muscle, two (8.7%) in the celomatic cavity, and two (8.7%) in the air bladder. From the 106 fishes positive to the infection by larvae of

Avaliação da predação de Podocnemis expansa e Podocnemis unifilis (Testudines, Podocnemididae) no rio Javaés, Tocantins

Podocnemis expansa e P. unifilis são animais de vida longa, com uma demorada maturação sexual, o que influencia uma baixa taxa de substituição de indivíduos. Suas populações são caracterizadas por uma pequena mortalidade dos animais adultos, mas alta taxa de mortalidade de filhotes e embriões. Sendo a predação natural de ninhos e filhotes um dos fatores mais importantes do baixo sucesso de eclosão dessas espécies. No rio Javaés, os ovos e recém-eclodidos podem ser predados por uma grande diversidade de animais: dentre as aves, urubus (Coragyps atratus e Cathartes aura), carcará (Polyborus plancus), jaburu (Jabiru mycteria); lagartos (Tupinambis teguixin) e mamíferos de pequeno porte, coati (Nasua nasua) e cachorro-do-mato (Cerdocyon thous). Do total anual de desovas de P. unifilis em média 65,98% são predadas, sendo 41,68% de forma total e 24,30% parcialmente. Enquanto que apenas 5,31% das ninhadas de P. expansa são sempre parcialmente predadas. Dentre os predadores aquáticos existem diversos peixes, principalmente piranhas (Serrasalmus nattereri) e jacarés (Melanosuchus niger e Caimam crocodilus). Os predadores das fêmeas de P. unifilis são: jacaré-açu (Melanosuchus niger), onça-pintada (Panthera onca) e onça-parda (Puma concolor). Enquanto que as fêmeas de P. expansa em postura, somente são predadas por P. onca. As fêmeas de P. unifilis em postura são predadas num total médio de 3,93% anualmente, enquanto que para P. expansa a média anual é 5,66% das fêmeas.

Distribuição e alimentação de duas espécies simpátricas de piranhas Serrasalmus maculatus e Pygocentrus nattereri (Characidae, Serrasalminae) do rio Ibicuí, Rio Grande do Sul, Brasil

Duas espécies de piranhas ocorrem no rio Ibicuí, um dos principais afluentes do rio Uruguai. Com o objetivo de analisar a distribuição e a alimentação destas espécies, foram realizadas coletas de dezembro de 1999 a janeiro de 2002, utilizando-se diferentes artes de pesca em três pontos do rio, sendo que cada ponto foi amostrado em dois ambientes (lêntico e lótico). Foram capturados 203 indivíduos de Serrasalmus maculatus Kner, 1858 e 86 de Pygocentrus nattereri Kner, 1858, sendo que a maior captura de ambas as espécies ocorreu no ambiente lêntico e próximo ao rio Uruguai, onde P. nattereri parece estar mais concentrada. O número de exemplares capturados por horário não apresentou variações significativas em P. nattereri enquanto que S. maculatus apresentou a maior captura na revisão da meia-noite. Juvenis de S. maculatus (2-4 cm de comprimento padrão) consumiram preferencialmente nadadeiras e insetos. Nas demais classes de tamanho de ambas as espécies, restos de peixes foi o alimento predominante, havendo sobreposição alimentar intra e interespecífica nas maiores classes (8-16 cm e >16 cm de comprimento padrão). Não foram constatadas diferenças no índice de repleção entre os horários e os ambientes para as duas espécies.

The inverted trophic cascade in tropical plankton communities: impacts of exotic fish in the Middle Rio Doce lake district, Minas Gerais, Brazil

The present study deals with the ecological impacts of the introduction of two alien species of piscivorous fish in several lakes of the Middle Rio Doce lake district in Minas Gerais, Brazil. It was demonstrated that these effects were not restricted only to the fish community. The introduction of the predatory red piranha Pygocentrus nattereri and the tucunaré Cichla cf. ocellaris caused not only a sharp decrease in the number of native fish species, but also major shifts in other trophic levels. Just after the fish were introduced, most lakes began to show conspicuous changes in phytoplankton species composition, in which Cyanophyceae gradually came to dominate. The zooplankton community lost several species, and in some cases, such as Lake Carioca, all the cladoceran species disappeared. On the other hand, invertebrate predators, represented by the dipteran Chaoboridae, boomed in the lake, with higher densities of exotic species, probably as a result of the 'ecological release' by reduction of the original fish fauna. There was a general trend of species loss in different trophic levels. All these changes are apparently associated with decreases in water quality. The present situation in these lakes demands new approaches to the management and conservation of these ecosystems.

UM ENSAIO SOBRE A ADAPTAÇÃO DE <i>Pygocentrus nattereri</i> À VARIAÇÃO SAZONAL DAS ÁGUAS DO LAGO MAMIRAUÁ – RESERVA DE DESENVOLVIMENTO SUSTENTÁVEL MAMIRAUÁ

This study investigates habitat use of Pygocentrus nattereri Kner, 1858 at the highest m om ents of the flooding period (July) and during the low water period (October), and evaluates the hability to survive low oxygen concentrations and the production of sulphidric gas in the waters of Mamirauá Lake – Mamirauá Sustainable Development Reserve. 12 experimental samplings were taken at six sites in Mamirauá Lake, and at Paraná Apara. With two experiments, carried out inside the waterbodies and in aquarium , we evaluated the effect of low D.O. concentration levels in the water on P. nattereri. Results show that even under
 restraining conditions of oxygenation in the water, P. nattereri are able to keep their vital functions. Different situation is observed when the waters of Mamirauá Lake produce high concentrations of suphidric gas, and the individuals of P. nattereri die under this circunstance.

Effect of seasonality and trophic group on energy acquisition in Amazonian fish

Abstract – The influence of hydrologic cycle and trophic groups on the energy content of food was investigated for five fish species from a Central Amazonian floodplain area. Sampling was carried out monthly using gillnets of different mesh sizes immersed in water for 24 h. We examined the presence and absence of food in fish stomachs and those with food were analysed and their energy content determined. Amongst the trophic groups studied, the piscivores Acestrorhynchus falcirostris and Pygocentrus nattereri showed high numbers of empty stomachs throughout the sampling period and very high levels of energy density in their food, which may explain why they take food less frequently. On the other hand the invertivorous species Hemiodus sp. and Hoplosternum littorale and the herbivore Rhytiodus microlepis, need to take food very frequently. The energy of the piscivorous species’ stomach contents was not significantly different during the hydrologic cycle, whereas the invertivore and herbivore varied significantly, showing a general tendency of high levels of energy during high waters.

Environment‐related life‐history trait variations of the red‐bellied piranha Pygocentrus nattereri in two river basins of the Bolivian Amazon

Life‐history traits of Pygocentrus nattereri were compared in two populations inhabiting connected tributaries of the upper Madera River: the white water Mamoré River and the clear water Iténez River. As white waters provide better trophic conditions than clear waters, the size at maturity, fecundity, reproductive effort, condition and growth of P. nattereri should be greater in the more productive white water river (Mamoré) than in the less‐productive clear water river (Iténez). Breeding periods were highly seasonal and similar in both rivers and under strong influence of photoperiod. Oocyte size‐frequency distributions, together with the frequent occurrence of recovering females indicated that an individual female spawns at least twice during the breeding season. As predicted, fish of the Mamoré were significantly larger at maturity and had higher fecundity and condition factor values than those of the Iténez. Fish from both rivers matured as yearlings. The higher growth potential of females was better expressed in the Mamoré than in the Iténez, where growth differences between sexes were weak. Females had a significantly better growth in the Mamoré than in the Iténez. The observed life‐history traits associations were consistent with the hypothesis of better trophic conditions in the Mamoré. In addition, previous genetic analyses evidenced that the colonization of the two basins is recent and that extant populations have very similar genetic backgrounds. This suggests that the observed variations in life‐history traits of P. nattereri are not related to historical factors (genetic drift) between two phylogeographically distinct lineages, but rather due to the contrasting environmental conditions in the white and clear waters.

Diversidade biológica da comunidade de peixes no baixo rio das Mortes, Mato Grosso, Brasil

O rio das Mortes é um dos principais cursos d’água do estado de Mato Grosso e o maior afluente, da margem esquerda, do rio Araguaia, sendo que a seção baixa do mesmo está inserida na planície do Bananal. Este estudo objetiva caracterizar ecologicamente a comunidade de peixes considerando um período sazonal: cheia e seca. A comunidade de peixes em estudo apresenta altos valores de diversidade (4,783 bits/indivíduos do Índice de Shannon-Wiener), riqueza de espécies (66 espécies amostradas) e abundância de indivíduos (659 indivíduos) durante o período de seca, onde as espécies mais abundantes foram Pygocentrus nattereri Kner, 1858 e Boulengerella cuvieri (Agassiz, 1829). Ageneiosus inermis (Linnaeus, 1766) e Rhaphiodon vulpinus Agassiz, 1829 foram mais abundantes na época cheia. A interação entre a comunidade de peixes e a planície de inundação apresenta um padrão comparável a este observado em planícies de inundação na região Neotropical.

Spinal Nerve Innervation to the Sonic Muscle and Sonic Motor Nucleus in Red Piranha, Pygocentrus nattereri (Characiformes, Ostariophysi)

The red piranha, Pygocentrus nattereri, produces sounds by rapid contractions of a pair of extrinsic sonic muscles. The detailed innervation pattern of the sonic muscle of the red piranha was investigated. The sonic muscle is innervated by branches (sonic branches) of the third (S3so), fourth (S4so), and fifth (S5so) spinal nerves. The average total number of nerve fibers contained in the right sonic branches (n = 5; standard length, SL, 71–85 mm) was 151.8 (standard deviation, SD, 28.3). The occipital nerve did not innervate the sonic muscle. The sonic motor nucleus (SMN) in the piranha was identified by tracer methods using wheat germ agglutinin-conjugated horseradish peroxidase; labeled sonic motor neurons were only observed on the side ipsilateral to the sonic muscle injected with the tracer. In the transverse sections, the labeled sonic motor neurons were located in the dorsal zone (mainly large and medium neurons) and in the ventral zone (mainly small neurons) of the ventral horn. In the horizontal sections, the labeled neurons formed a rostrocaudally elongated SMN from the level of the caudal part of the second spinal nerve root to the intermediate region between the fifth and sixth spinal nerve roots. The average number of the labeled neurons (n = 5; SL, 64–87 mm) was 152.6 (SD, 7.3). We conclude that the sonic muscles of the piranha are innervated by approximately 300 sonic motor neurons located only in the spinal cord.

Detection of betanodaviruses in apparently healthy aquarium fishes and invertebrates

Betanodaviruses are the causative agents of viral nervous necrosis (VNN) in cultured marine fish. A total of 237 apparently healthy aquarium fish, marine (65 species) and freshwater (12 species) fishes and marine invertebrates (4 species), which were stocked in a commercial aquarium in Seoul, South Korea, were collected from November 2005 to February 2006. The brains of the fish and other tissues of the invertebrates were examined by reverse transcriptase-polymerase chain reaction (RT-PCR) and nested PCR to detect betanodavirus. Positive nested PCR results were obtained from the brains of 8 marine fish species (shrimp fish Aeoliscus strigatus, milkfish Chanos chanos, three spot damsel Dascyllus trimaculatus, Japanese anchovy Engraulis japonicus, pinecone fish Monocentris japonica, blue ribbon eel Rhinomuraena quaesita, look down fish Selene vomer, yellow tang Zebrasoma flavesenes), 1 marine invertebrate species (spiny lobster Pamulirus versicolor), and 2 freshwater fish species (South American leaf fish Monocirrhus polyacanthus and red piranha Pygocentrus nattereri). The detection rate in nested PCR was 11/237 (4.64%). These subclinically infected aquarium fish and invertebrates may constitute an inoculum source of betanodaviruses for cultured fishes in the Korean Peninsula.

Sonic Motor Pathways in Piranhas with a Reassessment of Phylogenetic Patterns of Sonic Mechanisms among Teleosts

Sound production has evolved independently a number of times among teleost fishes. In most cases, sound is generated by fast contracting muscles that vibrate the swim bladder by way of their direct attachment (intrinsic muscles) or indirectly by way of other skeletal elements (extrinsic muscles). This study focuses on the red and black piranha, Pygocentrus nattereri and Serrasalmus rhombeus (superorder Ostariophysi, Order Characiformes), that have extrinsic swim bladder sonic muscles innervated by the third and fourth spinal nerves. This innervation pattern diverges from that found in most teleosts, including the closely related catfishes (Ostariophysi, Siluriformes), where sonic muscles are innervated by ventral occipital nerve roots that arise just caudal to the vagus nerve. Here, we tested the hypothesis that piranhas would also differ from most other teleosts in the location of their sonic motor neurons. Following biotin labeling of branches of the third and fourth spinal nerves that innervate the sonic muscles in the red and black piranha, sonic motor neurons were identified amongst other non-sonic motor neurons in the central part of the spinal cord, slightly ventrolateral to the central canal. To our knowledge, this is the first example of sonic motor neurons positioned entirely within the spinal cord. In the other species so far studied, sonic motor neurons form well-defined nuclei that extend from far caudal levels of the medulla into the rostral spinal cord and are located either within the ventral motor column or near the midline, close to or just ventrolateral to the fourth ventricle and central canal. A piranha-like pattern may be more widespread among characiforms and is likely present in other teleost orders, e.g., Sciaenidae (drumfishes), that also have sonic muscles innervated by spinal nerves.

Evaluation of the infectivity of Trichinella papuae and Trichinella zimbabwensis for equatorial freshwater fishes

The discovery of Trichinella species infecting poikilotherm vertebrates has opened new possibilities in the epidemiology of this parasite group. The aim of the present work was to investigate the infectivity of the two non-encapsulated species of Trichinella infecting both mammals and reptiles, Trichinella papuae and Trichinella zimbabwensis, for equatorial freshwater carnivore fishes. To this end, two species of piranhas, four Serrasalmus nattereri and four Serrasalmus rhombeus, were each inoculated per os with the two species of Trichinella larvae. Six days post infection (p.i.), one fish of each species inoculated with one of the two species of Trichinella was sacrificed. The intestines and celomatic cavities were searched for worms using dissection microscopy, and the presence of muscle larvae was evaluated by artificial digestion. The other 4 inoculated fish were sacrificed 60 days p.i. and similarly searched for the presence of worms. No larva or adult worms were detected in any organ or tissue at 6 or 60 days p.i. The lack of infectivity of T. papuae and T. zimbabwensis for fish suggests that the entozoic habitat of this animal does not represent a suitable environment for these two Trichinella species. More importantly, these data indicate that freshwater fishes, one of the food resources for crocodiles, caimans and alligators, are unlikely to play a role in the epidemiology of the known species of the genus Trichinella.