Resumo Neste estudo, determinamos os principais parâmetros reprodutivos do piau gordura, Leporinus piau, em duas seções da bacia do rio São Francisco. Entre maio de 2015 e abril de 2016, um total de 573 espécimes foram capturados de um ambiente lêntico (seção 1), o reservatório de Três Marias (RTM), e um ambiente lótico (seção 2), à jusante da RTM na confluência do rio São Francisco (RSF) com o rio Abaeté. A análise da atividade reprodutiva mostrou que L. piau se reproduz nas duas seções, mas fêmeas e machos da seção 1 apresentaram maiores valores de comprimento total, peso corporal, fator de condição de Fulton e índice gonadossomático em comparação com a seção 2. O dimorfismo sexual foi evidente na espécie com as fêmeas sendo maiores do que os machos. Além disso, os machos atingiram a primeira maturação gonadal em tamanho menor do que as fêmeas. O pico do estágio de maturação/maduro foi observado em novembro/abril para fêmeas e machos na seção 1 e em novembro/dezembro na seção 2, coincidindo com altas temperaturas e precipitação na região. Em ambas as seções do rio, L. piau apresentou características típicas de desova parcelada com período de desova prolongada e reproduz preferencialmente em ambientes lênticos.

Abstract In this study, we determined the main reproductive parameters of piau gordura, Leporinus piau, in two sections of the São Francisco River basin. Between May 2015 and April 2016, a total of 573 specimens were captured from a lentic environment (section 1), the Três Marias Reservoir (TMR), and a lotic environment (section 2), downstream of the TMR at the confluence of the São Francisco River (SFR) with the Abaeté River. Analysis of reproductive activity showed that L. piau from both sections reproduced, but females and males from section 1 exhibited higher total length, body weight, Fulton condition factor, and gonadosomatic index values, as compared to section 2. Sexual dimorphism was evident in the species, with females being larger than males. Moreover, males reached first gonadal maturation at a smaller size than females. The peak maturation/mature stage was observed in November/April for females and males in section 1 and in November/December in section 2, coinciding with high temperatures and precipitation in the region. In both sections of the river, L. piau exhibited the typical characteristics of partial spawning, with a prolonged spawning period, and preferential reproduction in lentic environments.

Resumo: Com o objetivo de avaliar a influência da barragem de Três Marias na reprodução da piranha branca, Serrasalmus brandtii, foram analisados 1569 exemplares capturados de junho de 2011 a maio de 2012 em três trechos da bacia do rio São Francisco: seção 1 = reservatório de Três Marias (RTM); seção 2 = segmento do rio São Francisco (SRF) imediatamente a jusante do RTM; e seção 3 = segmento RSF na confluência com o rio Abaeté. O comprimento total (CT), peso corpóreo (PC), índice de gonadossomático (IGS) e estágio de maturação gonadal foram determinados para cada amostra, enquanto o diâmetro do folículo vitelogênico, fecundidade absoluta (FA) e relativa (FR) foram determinadas para fêmeas. Nas três seções estudadas, a atividade reprodutiva foi registrada ao longo do ano, incluindo fêmeas desovadas e machos espermiados. Maiores frequências de fêmeas e machos na fase de maturação/maduro foram encontradas nos meses de novembro/dezembro e janeiro/fevereiro, coincidindo com o período de maior temperatura, precipitação e concentração de oxigênio dissolvido. O IGS médio e o diâmetro do folículo vitelogênico foram maiores nas seções 1 e 3 do que na seção 2 (P <0,05), enquanto FA e FR foram maiores na seção 1 (P <0,05) do que nas seções 2 e 3. Os resultados do presente estudo mostraram que S. brandtii teve menor desempenho reprodutivo na seção 2, provavelmente devido a perturbações térmicas causadas pela barragem, confirmando a influência das barragens na reprodução de peixes a jusante de reservatórios de usinas hidrelétricas.

Abstract: In order to assess the influence of the Três Marias dam on the reproduction of the white piranha, Serrasalmus brandtii, 1569 specimens captured from June 2011 to May 2012 in three sections of the São Francisco River basin were analyzed: section 1 = Três Marias reservoir (TMR); section 2 = São Francisco River (SFR) segment immediately downstream of TMR; and section 3 = SFR segment at the confluence with the Abaeté River. Total length (TL), body weight (BW), gonadosomatic index (GSI), and gonadal maturation stages were determined for each specimen, while vitellogenic follicle diameter, and absolute (AF) and relative (RF) fecundities were also determined for females. Reproductive activity, including spawned females and spermed males, was recorded throughout the year in the three river segments. Higher frequencies of females and males at the maturing/mature stage were found in the November/December and January/February, which coincided with the period of higher temperature, rainfall, and dissolved oxygen concentration. Mean GSI and vitellogenic follicle diameter were higher in sections 1 and 3 than in section 2 (P <0.05), while AF and RF were higher in section 1 (P <0.05) than in sections 2 and 3. The results of the present study showed that S. brandtii had lower reproductive performance in section 2, probably due to thermal disturbances caused by the dam, thus confirming the influence of dams on the reproduction of fish downstream from hydroelectric plant reservoirs.

ResumenTeniendo en cuenta que la morfología de las gónadas es un parámetro importante para la comprensión de la biología de la reproducción, las relaciones filogenéticas y estudios sistemáticos, el objetivo principal de este estudio fue realizar un análisis comparativo de la morfología de ovarios maduros y testículos en seis especies de peces de la familia Anostomidae. Un total de 212 especímenes, con las gónadas en maduración, fueron capturados en el río São Francisco, área de embalse de Três Marias, en el sureste de Brasil, entre agosto 2008 y diciembre 2010. Las seis especies analizadas mostraron ovarios maduros de un color grisáceo. En los ovocitos vitelogénicos (VO), los alvéolos corticales (CA) están compuestos por pequeñas vesículas en todas las especies de Leporinus, pero en Leporellus vittatus y Schizodon knerii los CA son grandes vesículas. Los CA de todas las especies mostraron, no obstante, un contenido histoquímico similar. La zona pelucida se compone de dos capas en todas las especies, pero es más gruesa en S. knerii (11.5 ± 1.8 µm) que en L. vittatus (9.0 ± 0.8 µm) y las especies de Leporinus (3.5 ± 0.6 - 8.7 ± 0.9 µm). Las células foliculares de los VO son, cúbico y prismática en polos animales y vegetativos de S. knerii (22.3 ± 3.2 y 61.1 ± 9.6 µm), respectivamente, y escamosas en las otras especies (1.3 ± 0.3 - 1.6 ± 0.3 µm). Las hembras de S. knerii y los machos de L. vittatus mostraron menor GSI que las otras especies evaluadas. Todas las especies presentan una morfología testicular similar a la mayoría de los Characiformes neotropicales, los cuales poseen testículos espermatogonias sin restricciones y organización tubular anastomosis de los túbulos seminíferos. Las diferencias fenotípicas en los VO entre las especies de Anostomidae confirman la posición taxonómica de S. knerii como género diferente en relación a Leporinus y L. vittatus. A pesar de ser colocados en diferentes géneros, las características de los ovocitos vitelogénicos de L. vittatus son similares a los encontrados en los Leporinus estudiados.

AbstractIn fishes, gonad morphology is an important parameter to understand the reproductive biology, phylogenetic relationships and systematic studies. The main objective of this study was to make a comparative analysis of the morphology of mature ovary and testis in six fish species of the family Anostomidae. A total of 212 specimens, presenting maturing gonads, were captured from the São Francisco River, Três Marias Reservoir area, in Southeastern Brazil, between August 2008 and December 2010. The six analyzed species had mature ovaries and showed a grayish color. In vitellogenic oocytes (VO), cortical alveoli (CA) were composed by small vesicles in all Leporinus species, but in Leporellus vittatus and Schizodon knerii the CA were large vesicles. However, the CA of all species showed similar histochemical content. The pellucid zone consists of two layers to all species, but it was thicker in S. knerii (11.5 ± 1.8 µm) than in L. vittatus (9.0 ± 0.8 µm) and Leporinus species (3.5 ± 0.6 - 8.7 ± 0.9 µm). Follicular cells of the VO were respectively cubic and prismatic in animal and vegetative poles of S. knerii (22.3 ± 3.2 and 61.1 ± 9.6 µm), and squamous in the other species (1.3 ± 0.3 - 1.6 ± 0.3 µm). Females of S. knerii and males of L. vittatus showed lower values of gonadosomatic index (GSI) than the other assessed species. All evaluated species presented testicular morphology similar to most neotropical Characiformes, with unrestricted spermatogonial testis and anastomosing tubular organization of seminiferous tubules. Phenotypical differences in the vitellogenic oocyte of Anostomidae fishes, confirmed the taxonomic position of S. knerii as different genus in relation to Leporinus and L. vittatus. Despite being placed in different genera, the characteristics of the vitellogenic oocytes of L. vittatus were similar to those found in the studied Leporinus.

ResumenEl desarrollo temprano de las larvas de peces es un proceso altamente dinámico y estudiarlo proporciona información importante sobre su desarrollo ontogénico, su crecimiento bioenergético, su comportamiento, las características taxonómicas para la identificación en entornos naturales, la identificación de las zonas de desove y la vigilancia de la población. Los primeros años de vida de Prochilodus argenteus y Prochilodus costatus fueron estudiados desde la eclosión hasta la completa absorción de la yema, con el fin de proporcionar conocimiento sobre los caracteres taxonómicos y el crecimiento y comportamiento, lo cual puede ser aplicado al desarrollo de la cría de larvas. Las larvas fueron obtenidas junto a la Estación de Hidrobiología y Acuicultura de Três Marias, Minas Gerais, donde fueron reproducidas artificialmente. Inmediatamente después de la eclosión, aproximadamente 100 larvas de cada especie fueron acondicionadas en dos incubadoras de plástico. El comportamiento de las larvas fue registrado diariamente y fueron recolectadas 14 larvas de cada especie para análisis morfológico del cuerpo. En el primer día después de la eclosión las larvas de P. costatus y P. argenteus presentaban cuerpos alargados y transparentes. El saco vitelino se llenó de glóbulos de vitelo individualizados. En las dos especies, la aleta embrionaria circundaba la región caudal del cuerpo, la retina no presentaba pigmentos y el intestino estaba obliterado. En el segundo día, en las larvas de ambas especies habían surgido cromatóforos dendríticos, la boca estaba obliterada y fue registrada una aleta pectoral. Las larvas presentaban 38-43 miómeros en P. costatus y 42-43 en P. argenteus. En las dos ecpecies la vejiga de gas estaba inflada y el lumen del intestino ya estaba abierto. En el tercer día, la boca tanto del P. costatus como del P. argenteus ya estaba abierta en una posición subterminal. La retina estaba pigmentada, los arcos branquiales tenían protuberancias laminares y estaban parcialmente cubiertos por el opérculo. En el cuarto día, el patrón de pigmentación se presentó con mayor intensidad; la boca ocupó una posición terminal, el saco vitelino fue casi completamente reabsorbido y las aletas pectorales y caudales presentaban rayos mesenquimales en ambas especies. El intestino mostró un amplio lumen, con la mucosa plegada y el epitelio con borde estriado. Las larvas de ambas especies mostraron un comportamiento similar de natación durante el periodo de prueba. Nuestro estudio provee conocimiento sobre aspectos morfofisiológicos, identificación de especies, desarrollo y crecimiento larval y características ontogénicas de dos peces subtropicales de importancia para la pesca comercial y deportiva.

AbstractEarly development of fish larvae is a highly dynamic process and its study may provide important information about ontogenetic development, bioenergetic growth, behaviour, taxonomic characteristics for identification in natural environments, identification of spawning areas, and population monitoring. With the aim to provide knowledge about their growth and behaviour, to support larval rearing, and also taxonomic purposes, we studied the life history of the Prochilodus argenteus and P. costatus from hatching until the complete absorption of the yolk. Larvae were obtained through artificial reproduction at the Hydrobiology and Aquaculture Station of Três Marias, Minas Gerais, Brazil. Immediately after hatching, 100 larvae of each species were put in two plastic incubators for conditioning. On a daily basis, larvae behavior was recorded and 14 larvae of each species were collected to analyse body morphology. On the first day after hatching, larvae of P. costatus and P. argenteus showed an elongated and transparent body; the yolk sac was filled with individualized yolk globules. In both species, the embryonic fin rounded the caudal region of the body, the retina was non-pigmented and the gut was obliterated. At the second day post-hatching, larvae of both species dendritic chromatophores had emerged, the mouth was obliterated and the pectoral fin was observed. The larvae showed 38-43 myomeres in P. costatus and 42-43 in P. argenteus. For both species, the gas bladder was inflated and the lumen of the gut was already open. On the third day post-hatching, the mouth of P. costatus and P. argenteus was already open in a sub-terminal position; the retina was pigmented; the gill arches had lamellar protrusions and were partially covered by the operculum. On the fourth day post-hatching, the pigmentation pattern was maintained with greater intensity; the mouth occupied a terminal position, the yolk sac was almost completely reabsorbed, and the pectoral and caudal fins showed mesenchymal rays in both species. The gut showed a broad lumen with folded mucosa and epithelium with striated border. The larvae of both species showed similar swimming behaviour. Our study provided understanding about the morphophysiological aspects, species identification, larval development and growth, and the ontogenic characteristics of two Neotropical fishes with importance for commercial and sports fishing. Rev. Biol. Trop. 64 (2): 537-546. Epub 2016 June 01.

RESUMO Investigamos o padrão de crescimento inicial do pacamã, Lophiosilurus alexandri , um bagre endêmico da bacia do rio São Francisco, Brasil. Larvas de pacamã foram mantidas numa canaleta horizontal de metal galvanizado durante 29 dias após a eclosão. Diariamente, coletamos circa 10 larvas (número total = 285) das quais obtivemos o comprimento total (variável independente) e 11 outras medidas corporais (variáveis dependentes). Fizemos regressões lineares nos dados log transformados para determinar o padrão de crescimento das medidas corporais e respectivo ponto de inflexão das curvas de crescimento. Exceto comprimento do tronco, largura do tronco e volume do saco vitelino, as demais medidas corporais apresentaram crescimento alométrico positivo até o respectivo ponto de inflexão, seguido de redução na taxa relativa de crescimento. Embora a largura do tronco apresentasse crescimento alométrico positivo, não foi detectado um ponto de inflexão significativo. O achatamento dorso-ventral da cabeça, presente nos adultos, mostrou-se evidente nas larvas com o acentuado crescimento alométrico de sua largura. Os barbilhões maxilares exibiram a maior taxa de crescimento. O extraordinário crescimento dos olhos e dos barbilhões maxilares e a habilidade adquirida para a captura de presas (como sugere o crescimento do comprimento bucal) reforçam a hipótese de prioridade de crescimento em que os órgãos essenciais são os primeiros a se desenvolverem.

ABSTRACT We investigated the early life growth pattern of pacamã, Lophiosilurus alexandri , a catfish endemic to the rio São Francisco basin, Brazil. Pacamã larvae were kept in a galvanized trough for 29 days after hatching. We collected approximately 10 larvae daily (total number = 285). We obtained from each specimen the total length (independent variable) and 11 other body measurements (dependent variables). We performed linear regressions on the log-transformed data to determine the growth pattern of the body measurements and the respective inflexion point on the growth curves. Except for trunk length, trunk width and yolk sac volume, the remaining body measurements showed a positive allometric growth coefficient up to the respective IP followed by a decrease in the rate of relative growth afterwards. Although trunk width presented a positive allometric growth, no significant inflexion point was detected. The dorsal-ventral head flattening seen in the adult pacamã was quickly expressed in the larvae as indicated by the large allometric growth of head width. Maxillary barbels showed the highest growth rate. The exceptionally high growth rates of eyes and maxillary barbels and the acquired ability to capture prey (as suggested by mouth length growth) strengthened the hypothesis of growth priorities in which the most essential organs develop first.

Levantamentos da avifauna urbana no Brasil tem aumentado nos últimos anos, embora nenhum deles consista de estudos a longo prazo que indiquem eventos de colonizações regionais ou desaparecimento de espécies. Neste estudo, apresentamos um levantamento da avifauna de um ecossistema urbano do sudeste brasileiro, efetuado ao longo de 30 anos, no campus da Pontifícia Universidade Católica de Minas Gerais, município de Belo Horizonte, estado de Minas Gerais. Dentro do campus há uma pequena reserva florestal adjacente a um pequeno lago. O inventário foi baseado principalmente em registros aleatórios ao longo de 1982-2013. Foram registradas 134 espécies de aves neste período. Entretanto, a avifauna atual é composta por 123 espécies. Um total de 97 espécies foi registrado na reserva, representada pelo fragmento florestal e pelo lago adjacente, das quais 44 foram exclusivas a esta área. Todavia, a maior parte das espécies de aves que ocorrem atualmente na área de estudo é independente (N = 51) ou semi-dependente (N = 46) de florestas. Há um predomínio de espécies insetívoras (N = 43) e onívoras (N = 29). A avifauna atual é representada por 15 espécies migratórias, que podem ser encontradas tanto na área urbanizada quanto no remanescente florestal. Entretanto, a maioria das espécies (N = 75) é residente na área, incluindo três invasoras, enquanto outras (N = 28) são representadas por visitantes ocasionais. O restante das espécies foi possivelmente introduzido na área. Houve 11 casos de desaparecimento de espécies, que incluem espécies típicas de matas, áreas úmidas e ambientes rurais. Também comentamos sobre colonizações recentes e sobre possíveis efeitos do isolamento nas aves. Provavelmente, a maior parte das espécies dependentes de florestas está próxima à extinção local no fragmento florestal. Assim, o presente levantamento pode ser útil como uma base de informações para monitoramentos de longo prazo sobre os efeitos da urbanização sobre esta comunidade de aves.

Urban avifaunal surveys in Brazil have been increasing in recent years, despite none of them consisting of long-term studies indicating events of regional colonization and/or missing species. Here, we present an avifaunal survey of an urbanized ecosystem in southeastern Brazil, carried out along 30 years, on the campus of the Pontifícia Universidade Católica de Minas Gerais, municipality of Belo Horizonte, Minas Gerais state. Inside the campus there is a forest reserve adjacent to a small lake. The inventory was mainly based on opportunistic records from the years 1982-2013. We recorded 134 bird species along the past 30 years. However, the present avifauna is composed of 123 species. A total of 97 species was recorded in the reserve, including the forest fragment and the adjacent lake, of which 44 were exclusive to this area. Nevertheless, the majority of the current species found in the study area is forest independent (N = 51) or semi-dependent (N = 46). There is a predominance of insectivorous (N = 43) and omnivorous (N = 29) species. The current avifauna is represented by 15 migratory species, which can be found both in the urbanized area and in the forest remnant. However, the majority of the species (N = 75) is resident in the area, including three invasive species, whereas few others (N = 28) are occasional visitors. The remaining species were probably introduced in the area. There were 11 cases of disappearing species, which include typical forest birds, and also species typical of wetlands and rural environments. We also comment on recent colonization and on the possible effects of isolation on birds. Probably, the majority of forest-dependents are on the brink of extinction in the forest fragment. Thus, the species' list provided here can be useful as a database for monitoring long-term effects of urbanization on this bird community.

A molecular phylogenetic analysis based on mitochondrial 16S ribosomal DNA and Control Region sequences from native and introduced populations was undertaken, in order to characterize the introduction of Cichla (peacock bass or tucunaré) species in Brazil. Mitochondrial DNA haplotypes found in introduced fish from Minas Gerais state (southeastern Brazil) clustered only with those from native species of the Tocantins River (Cichla piquiti and C. kelberi), thereby suggesting a single or, at most, few translocation acts in this area, even though with fish from the same source-population. Our study contributes to an understanding of the introduction of Cichla in regions of Brazil outside the Amazon basin, and adds phylogenetic data to the recently describe Cichla species, endemic from the Tocantins-Araguaia basin.

Estudou-se a estrutura testicular dos seguintes peixes Siluriformes: Pimelodus maculatus (Lacepède, 1803), Iheringichtys labrosus (Lütken, 1874) e Conorhynchos conirostris (Valenciennes, 1840). Os testículos foram dissecados e divididos anatomicamente em regiões cranial e caudal. As franjas dos testículos em maturação foram contadas e mediu-se o comprimento das mesmas. O teste t de Student foi utilizado para verificar diferenças significativas entre o comprimento das franjas das duas regiões. Para estudo histológico, testículos inteiros de cada espécie, em repouso e em maturação, foram fixados em líquido de Bouin por 6-8 horas e submetidos às técnicas histológicas de rotina. Utilizaram-se técnicas histoquímicas clássicas para detectar carboidratos e proteínas. Os testículos das espécies estudadas são órgãos pares e franjados. Histologicamente, as franjas da região cranial de todas as espécies são espermatogênicas, com células da linhagem em mesma fase de desenvolvimento contidas em cistos. As franjas da região caudal de C. conirostris são também espermatogênicas, enquanto P. maculatus e I. labrosus apresentam franjas caudais exclusivamente secretoras. Histoquímicamente detectou-se na secreção das franjas caudais de P. maculatus glicoproteínas neutras, glicoconjugados ácidos carboxilados, incluindo sialomucinas e glicoconjugados ácidos e sulfatados e em I. labrosus glicoproteínas neutras. Houve diferenças significativas entre o comprimento das franjas das regiões cranial e caudal para todas as espécies estudadas.

The testes structure of the following Siluriformes was studied: Pimelodus maculatus (Lacepède, 1803), Iheringichtys labrosus (Lütken, 1874) and Conorhynchos conirostris (Valenciennes, 1840). The testes of these species were dissected into cranial and caudal regions. The fringes of mature testes were counted and measured. Student's t-test was used to identify significant differences between fringe lengths of the two regions. To study the whole testes of each species in its resting and mature stage, testes were fixed in Bouin liquid for 6-8 hours and submitted to routine histological techniques. Standard histochemical techniques were used to detect carbohydrates and proteins. The testes of all species were paired and fringed organs. Histologically, cranial fringes of all species were spermatogenic with cells inside cysts at the same phase of development. Caudal fringes of C. conirostris were spermatogenic; while P. maculatus and I. labrosus showed caudal fringes only during secretion. Histochemically, neutral glycoproteins, acid glycoconjugates, acid carboxilates, sialomucines, and acid and sulfates glycoconjugates were detected in the caudal fringe secretions of P. maculatus; and neutral glycoproteins in I. labrosus. Significant differences between the fringe lengths of the cranial and caudal regions were found for all the species studied.

A biologia reprodutiva de Iheringichthys labrosus (Lütken, 1874) foi estudada no reservatório de Furnas, Minas Gerais, Brasil, utilizando-se técnicas biométricas, macroscópicas e microscópicas. Capturaram-se, bimestralmente, 323 machos e 817 fêmeas, utilizando-se redes de emalhar no período de agosto de 1993 a julho de 1994. A atividade secretora dos túbulos da região caudal dos testículos foi analisada durante o período reprodutivo. Machos e fêmeas encontravam-se em atividade reprodutiva durante todo ano com pico de maturação avançada/maduro de outubro a janeiro de desovado/espermiado de fevereiro a maio. O longo período de desova e a alta freqüência de fêmeas parcialmente desovadas indicaram que a espécie tem desova do tipo parcelado, com desenvolvimento assincrônico dos ovócitos. A espécie desova no reservatório e/ou em tributários nas suas proximidades. O epitélio dos túbulos da região caudal dos testículos apresentou alta atividade secretora durante o estádio maturação avançada/maduro, estando essa atividade ausente no estádio de repouso. O índice gonadossomático acompanhou a maturação das gônadas e o índice hepatossomático apresentou-se mais baixo na maturação avançada/maduro, sugerindo transferências de substâncias hepáticas para os ovários. As variações dos índices de repleção do estômago, de gordura celômica e o fator de condição indicaram que os peixes alimentam-se menos e consomem reservas graxas no período reprodutivo.

The reproductive biology of Iheringichthys labrosus (Lütken, 1874) was studied in Furnas reservoir, Minas Gerais, Brazil. The fishes, 323 males and 817 females, were captured bimonthly from August 1993 to July 1994 by using gill nets with 3-10 cm mesh size. Gonadal maturation of the specimens was analyzed through macro and microscopical characteristics of the gonads. The secretory activity of the tubules of the caudal region of the testis was analyzed during the maturational testicular cycle. Females and males were in reproductive activity throughout the year in the reservoir. The peak of advanced maturation/mature stages occurred from October to January and of spawned/spent from February to May. The spawning of I. labrosus was identified as fractional or multiple type: occurring in the reservoir or in tributaries around it. The oocyte development of the species was asynchronous as different clusters of oocytes occurred simultaneously in the ovarian parenchyma. The epithelium of the tubules of the caudal region of the testis was in high secretory activity during advanced maturation/mature stage and this activity was absence in resting. The gonadosomatic index followed gonadal maturation, and the hepatosomatic index of females was lowest in advanced maturation/mature probably due the contribution of the liver in the vitellogenesis. The variations of the stomach repletion index, coelomic fat and condition factor indicated that the feeding activity was reduced and that the energetic reserves were consumed during the reproductive period.

The larval ontogeny and swimming behavior of the characid fish Salminus brasiliensis (Cuvier, 1816) were studied under experimental laboratory conditions, from hatching to yolk absorption. At day 1, the larvae were transparent, with sparse dendrite chromatophores and a well-developed adhesive organ on the head. The retinal epithelial cells were initiating pigmentation. The branchial arches were at the initial phase of differentiation. The larvae were able to perform only vertical displacements and, when resting on the tank bottom, remained in lateral decumbency, in groups of 3 to 15 larvae. On day 2, the mouth was open, with conical teeth, and the digestive tube presented lumen and folded mucosa. The gaseous bladder and pectoral fins also were in differentiation. The larvae performed vertical and horizontal movements, adhered to the water surface by means of the adhesive organ or formed groups of three to six on the tank bottom. On day 3, the adhesive organ turned dorsal, the retina was pigmented, the digestive tube mucosa showed goblet cells, and the yolk sac exhausted. The larvae were now scattering in the water column forming no groups on the bottom.