Observation of the embryonic development in Pseudoplatystoma coruscans (Siluriformes: Pimelodidae) under light and scanning electron microscopy

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Coeficientes de digestibilidade aparente da proteína e energia de alguns ingredientes utilizados em dietas para o pintado (Pseudoplatystoma coruscans)

O presente trabalho foi desenvolvido com o objetivo de determinar os coeficientes de digestibilidade aparente da proteína e da energia dos principais alimentos utilizados na formulação de dietas para alevinos de pintado. Foram utilizados 600 alevinos com peso médio inicial de 9,80 ± 1,48 g e comprimento total médio de 13,00 ± 1,00 cm. Na coleta de fezes, foi utilizado o sistema de Guelph modificado. As 12 dietas-teste foram constituídas por 69,50% de uma dieta de referência, 0,50% de óxido de cromo (marcador inerte) e 30% do ingrediente estudado. Após receberem as dietas teste durante três dias, os peixes foram transferidos para os aquários de coleta (incubadoras de fibra de vidro de 80 litros de capacidade), onde as fezes foram coletadas em intervalos de meia hora. Com base nos coeficientes de digestibilidade da fração protéica, os alimentos que apresentaram maior aproveitamento para esse nutriente foram: farinha de peixe (84,14%), farelo de soja (67,10%), milho (64,18%) e farinha de vísceras de aves (61,25%). Foram observados valores razoáveis somente para a digestibilidade do conteúdo energético em metade dos ingredientes estudados; para as farinhas de peixe, milho, soja integral tostada e os farelos de soja, de trigo e de arroz, os coeficientes médios foram: 72,80; 57,39; 64,95; 61,66; 53,20 e 51,84%, respectivamente. A farinha de peixe foi o melhor ingrediente para o pintado (45,38% PD e 2790,42 kcal ED/kg), seguido do farelo de soja (30,86% PD e 2708,45 kcal ED/kg), da soja integral tostada (18,34% PD e 3121,06 kcal ED/kg), do milho (5,86% PD e 2691,53 kcal ED/kg) e do farelo de trigo (8,08% PD e 2265,13 kcal ED/kg).

Chemical cues related to conspecific size in pintado catfish, Pseudoplatystoma coruscans

The pintado (Pseudoplatystoma coruscans) is a ferocious carnivorous catfish with evident cannibalistic behaviour; its nocturnal habits are related to its ability to use predominately chemical sensorial modalities. This study investigated whether the pintado distinguishes conspecifics of different body sizes using chemical cues, which may reflect different physiological conditions such as hunger or stress. Pintados were observed when receiving water conditioned by either larger or similar-size conspecifics. A control group consisted of pintados receiving unconditioned water. Twelve repetitions were used for each condition. Feeding-like behaviours were investigated in the receiver fish and showed that they responded only to the conditioned water. Furthermore, a higher frequency of responses occurred when the water was conditioned by a similar-size conspecific. Thus, it is concluded that pintados are able to recognize conspecific size by chemical cues related to size and that this ability contributes to the individual's decision making on whether to approach or to avoid the conspecific.

Morphological deformities in the osseous structure in spotted sorubim Pseudoplatystoma coruscans (agassiz & spix, 1829) with vitamin c deficiency

A vitamina C é essencial para dietas de peixe porque muitas espécies não conseguem sintetizá-la. Esta vitamina é necessária par a formação de cartilagem e matriz óssea. Além disso, age como antioxidante e melhora as resposta do sistema imunológico. O presente trabalho investigou os efeitos da suplementação de vitamina C em dietas para alevinos de pintado (Pseudoplatystoma corruscans) pela incidência de deformidades na estrutura óssea e cartilaginosa. O ascorbil polifosfato (AP) foi utilizado como fonte de vitamina C em dietas para alevinos de pintado durante o período de três meses. Seis dietas foram formuladas: uma dieta controle (0 mg de vitamina C / kg) e cinco dietas 500, 1.000, 1.500, 2.000 e 2.500 mg de AP / kg. Os peixes alimentados sem suplementação de vitamina C apresentaram deformidades óssea na cabeça e mandíbula e fragilidade de nadadeiras. Assim, a dieta de 500 mg de AP/kg foi suficiente para prevenir a ocorrência de deformidades, e a ausência desta vitamina prejudica o desenvolvimento ósseo de juvenis de pintados.

Produção de juvenis de Pseudoplatystoma coruscans (Agassiz, 1829) com dietas vivas e formuladas

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Treinamento alimentar de pintado Pseudoplatystoma coruscans (Agassiz, 1829): sobrevivência, crescimento e aspectos econômicos

Pós-graduação em Aquicultura - FCAV

Morphological deformities in the osseous structure in spotted sorubim Pseudoplatystoma coruscans (agassiz & spix, 1829) with vitamin c deficiency

A vitamina C é essencial para dietas de peixe porque muitas espécies não conseguem sintetizá-la. Esta vitamina é necessária par a formação de cartilagem e matriz óssea. Além disso, age como antioxidante e melhora as resposta do sistema imunológico. O presente trabalho investigou os efeitos da suplementação de vitamina C em dietas para alevinos de pintado (Pseudoplatystoma corruscans) pela incidência de deformidades na estrutura óssea e cartilaginosa. O ascorbil polifosfato (AP) foi utilizado como fonte de vitamina C em dietas para alevinos de pintado durante o período de três meses. Seis dietas foram formuladas: uma dieta controle (0 mg de vitamina C / kg) e cinco dietas 500, 1.000, 1.500, 2.000 e 2.500 mg de AP / kg. Os peixes alimentados sem suplementação de vitamina C apresentaram deformidades óssea na cabeça e mandíbula e fragilidade de nadadeiras. Assim, a dieta de 500 mg de AP/kg foi suficiente para prevenir a ocorrência de deformidades, e a ausência desta vitamina prejudica o desenvolvimento ósseo de juvenis de pintados.

Sustentabilidad de la Pesquería Artesanal del Río Bermejo.

Este trabajo es el resultado de la tesis de Maestría en Recursos Naturales y Medio Ambiente (Orientación Recursos Faunísticos), realizada por el autor en la Facultad de Ciencias Naturales de la Universidad Nacional de Salta y bajo la dirección del Dr. Sergio Gustavo Mosa. La pesca artesanal con fines comerciales es practicada en el sector salteño del Río Bermejo desde hace décadas, por pobladores de localidades ribereñas como Orán, Embarcación y Rivadavia Banda Sur, los cuales pescan hasta el límite Salta – Chaco, dependiendo de la época del año. Esta pesquería se desarrolló por más de 50 años fuera del marco de las normas legales vigentes en la provincia (Ley 5513), siendo una actividad marginal perseguida por la justicia, y mal vista por la opinión pública en general. Entre Julio de 2001 y Julio de 2003, la Cooperativa de Pescadores Artesanales “La Unión” fue habilitada como empresa pesquera comercial de tipo artesanal por la Secretaria de Medio Ambiente y Desarrollo Sustentable de Salta. El monitoreo de esta actividad fue efectuado por la Cátedra de Piscicultura y Pesquerías (IRNED) de la Facultad de Ciencias Naturales de la Universidad Nacional de Salta. Las reglamentaciones y regulaciones legales de esta actividad se tomaron originariamente bajo el principio de precaución ante la falta de conocimiento científico. A la luz de la nueva información colectada, algunas de ellas resultan contrarias al principio prioritario de la gestión pesquera, el cual propone: Obtener la mejor utilización posible del recurso en provecho de la comunidad, recordando que mejor utilización implica mayor captura, mejor precio, más ganancias y más empleo. La presente Tesis de Maestría demuestra la sustentabilidad de la pesquería artesanal en el Bermejo, tanto desde a) el punto de vista biológico, analizando las capturas en función de las normas y reglamentaciones legales vigentes y de la biología y hábitos reproductivos de cada especie, como desde b) el punto de vista económico, teniendo en cuenta la relación costo-beneficio y las posibles alternativas para optimizar la misma. Asimismo, formula una serie de recomendaciones destinadas a mejorar la gestión pesquera. Para las 4 especies más importantes de la pesquería: sábalo Prochilodus lineatus, surubí Pseudoplatystoma coruscans, dorado Salminus brasiliensis y bagre blanco Pimelodus albicans, a) los cupos asignados para la captura anual por especie no son alcanzados; b) las tallas mínimas de captura observadas superan las tallas mínimas de captura autorizadas; c) las tallas medias de captura se encuentran muy por encima de las tallas medias de madurez sexual; d) la captura exclusiva de ejemplares maduros para todas las especies prueba que el grueso del stock pesquero ha podido superar por lo menos un evento reproductivo antes de ser capturado; e) el actual período de veda resulta demasiado amplio por lo que uno de dos meses, de mediados de noviembre a mediados de enero resultaría biológicamente adecuado. En cuanto a la sustentabilidad económica de la actividad, cada unidad económica de pesca debe realizar entre 45 y 50 excursiones de pesca anuales para obtener rendimientos económicos equivalentes a un ingreso mensual de aproximadamente $ 1000. (PDF tiene 92 paginas.)

Hunger suppresses the onset and the freezing component of the antipredator response to conspecific skin extract in pintado catfish

Although the skin of an injured conspecific releases alarm substance in some fish species, it has been shown that such damage induces feeding behaviour rather than an alarm reaction under conditions of food scarcity. We studied chemical communication associated with this paradox in a Brazilian catfish, the pintado (Pseudoplatystoma coruscans). In preliminary tests pintado were confirmed to demonstrate an alarm reaction to conspecific skin extract. In the experiment we investigated whether skin extract of pintado induces either alarm response (panic or alert component) or feeding in hungry conspecifics. Fish feed-deprived for eight days and fed control fish were exposed to either conspecific skin extract or distilled water (as a control). Alarm reaction was restricted to the skin extract treatment and occurred in the fish irrespective of their hunger state, but the components of this response were significantly affected by hungry. Fed fish showed a complete alarm reaction (dashing and freezing behaviours). Feed-deprived fish exhibited only part of this biphasic response, the dashing component. We conclude that chemicals from injured fish elicit an alarm reaction, which is partially inhibited by feeding motivation.

Female pintado catfish choose well-fed males

This study tested the preference of pintado catfish females (Pseudoplatystoma coruscans) for associating with well-fed or food-deprived males in simultaneous choice tests. Females were tested under three different treatments in which: (1) females could choose on the basis of multiple cues from the well-fed or food-deprived males (visual plus chemical); (2) only chemical cues were presented; (3) only visual cues were presented. Females chose well-fed males when chemical cues were presented (either visual + chemical or only chemical cues). When only visual cues were presented, females spent an equal amount of time in the choice apparatus compartments. Chemical signals, either directly through control of pheromone production, or indirectly by excreted metabolites, are likely to be an important source of information about nutritional condition in mating choice.

Henneguya pseudoplatystoma n. sp causing reduction in epithelial area of gills in the farmed pintado, a South American catfish: Histopathology and ultrastructure

The present study is part of an ongoing investigation into the characteristics of Myxozoan parasites of Brazilian freshwater fish and was carried out using morphology, histopathology and electron microscopy analysis. A new Myxosporea species (Henneguya pseudoplatystoma) is described causing an important reduction in gill function in the farmed pintado (a hybrid fish from a cross between Pseudoplatystoma corruscans and Pseudoplatystoma fasciatum), which is a commercially important South American catfish. From a total of 98 pintado juveniles from fish farms in the states of Sao Paulo and Mato Grosso do Sul (Brazil), 36 samples (36.7%) exhibited infection of the gill filaments. infection was intense, with several plasmodia occurring on a same gill filament. The plasmodia were white and measured up to 0.5 mm in length; mature spores were ellipsoidal in the frontal view, measuring 33.2 +/- 1.9 mu m in total length, 10.4 +/- 0.6 mu m in body length, 3.4 +/- 0.4 mu m in width and 22.7 +/- 1.7 mu m in the caudal process. The polar capsules were elongated, measuring 3.3 +/- 0.4 mu m in length and 1.0 +/- 0.1 mu m in width and the polar filaments had six to seven turns. Histopathological analysis revealed the parasite in the connective tissue of the gill filaments and lamella. No inflammatory process was observed, but the development of the plasmodia reduced the area of functional epithelium. Ultrastructural analyses revealed a single plasmodial wall, which was in direct contact with the host cells and had numerous projections in direction of the host cells as well as extensive pinocytotic canals. A thick layer (2-6 mu m) of fibrous material and numerous mitochondria were found in the ectoplasm. Generative cells and the earliest stage of sporogenesis were seen more internally. Advanced spore developmental stages and mature spores were found in the central portion of the plasmodia. (C) 2009 Elsevier B.V. All rights reserved.

Host-parasite-environment relationship, morphology and molecular analyses of Henneguya eirasi n. sp parasite of two wild Pseudoplatystoma spp. in Pantanal Wetland, Brazil

A new myxosporean species, Henneguya eirasi n. sp., is described parasitizing the gill filaments of Pseudoplatystoma corruscans and Pseudoplatystoma fasciatum (Siluriformes: Pimelodidae) caught in the Patanal Wetland of the state of Mato Grosso, Brazil. The parasite formed white, elongated plasmodia measuring up to 3 mm. Mature spores were ellipsoidal in the frontal view, measuring 37.1 +/- 1.8 mu m in total length, 12.9 +/- 0.8 mu m in body length, 3.4 +/- 0.3 mu m in width, 3.1 +/- 0.1 mu m in thickness and 24.6 +/- 2.2 mu m in the caudal process. Polar capsules were elongated and equal in size, measuring 5.4 +/- 0.5 mu m in length and 0.7 +/- 0.1 mu m in width. Polar filaments had 12-13 coils. Histopathological analysis revealed that the parasite developed in the sub-epithelial connective tissue of the gill filaments and the plasmodia were surrounded by a capsule of host connective tissue. The plasmodia caused slight compression of the adjacent tissues, but no inflammatory response was observed in the infection site. Ultrastructure analysis revealed a single plasmodial wall connected to the ectoplasmic zone through numerous pinocytotic canals. The plasmodial wall exhibited numerous projections and slightly electron-dense material was found in the ectoplasm next to the plasmodial wall, forming a line just below the wall. Partial sequencing of the 18S rDNA gene of H. eirasi n. sp. obtained from P. fasciatum resulted in a total of 1066 bp and this sequence did not match any of the Myxozoa available in the GenBank. Phylogenetic analysis revealed the Henneguya species clustering into clades following the order and family of the host fishes. H. eirasi n. sp. clustered alone in one clade, which was the basal unit for the clade composed of Henneguya species parasites of siluriform ictalurids. The prevalence of the parasite was 17.1% in both fish species examined. Parasite prevalence was not influenced by season, host sex or host size. (C) 2011 Elsevier B.V. All rights reserved.

Induced spawning of hatchery-raised Brazilian catfish, cachara Pseudoplatystoma fasciatum (Linnaeus, 1766)

In the months of January 2001 and 2002, female cachara Pseudoplatystoma fasciatum were selected during their first and second gonadal maturation (2 years and 7 months old and 3 years and 7 months old, respectively) with an of oocyte diameter of 937.5 mum (82.5% with central nuclei and 17.5% with peripheral nuclei). Nine females in first maturation received two doses of carp pituitary extract (CPE), 0.5 mg/kg and 5.0 mg/kg; seven received two doses of human chorionic gonadotropin (hCG), 5 and 10 IU/g; five received doses of 0.5 CPE mg/kg and 5 hCG IU/g (CPE+hCG); and four received 0.9% saline (saline). Nine females from CPE and seven from hCG presented oocytes with the same diameter at the moment of oocyte release (100% with germinal vesicle breakdown and fertilization rate of 53.44 +/- 18.3 and 54.81 +/- 11.8%; larvae number of 165,330 +/- 94.1 and 158,570 +/- 20.6, respectively). The five females from CPE+hCG did not respond to the hormonal treatment. The four females from the saline group did not ovulate. In January 2002, 6 of 15 selected females that were going through the second reproductive cycle received CPE (five received hCG and four received saline), showing oocyte diameters similar to the ones in the first maturation. At stripping, CPE females had an oocyte diameter of 1062.5 mum (the hCG females had oocyte diameters ranging from 937.5 to 1125.0 mum; fertilization rates of 56.08 +/- 30.9 and 81.90 +/- 17.3%; 364,547 +/- 244 and 633,129 +/- 190, larvae, respectively). The fertilization rates and larvae number were higher in the second gonad maturation, both for CPE and hCG. (C) 2004 Elsevier B.V. All rights reserved.

Histopatologia de fígado, rim e baço de piaractus mesopotamicus, prochilodus lineatus e pseudoplatystoma fasciatum parasitados por myxosporídios, capturados no Rio Aquidauana, Mato Grosso do Sul, Brasil

Este estudo descreveu a histopatologia de rim, baço e fígado de Piaractus mesopotamicus, Prochilodus lineatus e Pseudoplatystoma fasciatum, parasitados por mixosporídios, capturados no Rio Aquidauana, MS. Após necropsia, amostras do fígado, rim cefálico e baço foram colhidas, fixadas em formalina a 10 % tamponada e processadas de acordo com a rotina histológica. Os cortes foram feitos à espessura de 5 μm e corados com hematoxilina-eosina. Foram encontrados Myxobolus porofilus em P. lineatus, M. colossomatis em P. mesopotamicus e Myxobolus spp. nas três espécies de hospedeiros. Cistos de mixosporídios no exame histopatológico foram vistos no fígado e baço de P. mesopotamicus. Mais de 50% das amostras de fígado de P mesopotamicus e P lineatus apresentou hepatodistrofia difusa. Mais de 80 % das amostras de fígado de P. fasciatum apresentou formações hialinas concêntricas e esteatose em 50% das amostras. em 95,23 % das amostras de rins de P. mesopotamicus, foram observadas alterações teciduais, e em mais de 60 % dos casos nefrodistrofia difusa moderada e congestão de sinusóides glomerulares. Alterações teciduais nas amostras de rins de P. lineatus foram observadas em menos de 20 % da amostra. No baço dos peixes ora examinados não foram encontradas lesões dignas de relato.