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The development of hydropower production in the north of the Andes of South America has focused on the Magdalena basin. For this basin, it is reported that 68 % of the fish species are endemic and the effects that these structures produce on their assemblages in high mountain rivers have not been studied. This work answers the questions associated with the characteristics that describe the fish assemblage and the influence that some environmental variables influence on their distribution during the dry and rainy hydrological periods in the area of influence of two reservoirs. Seven fish species were caught, four of these are not native from the basin. No significant differences in abundances were found between aquatic systems and between climatic seasonality. The richness was higher in the streams and rivers. The assemblages changed according to the aquatic system; in reservoirs, the non-native species Micropterus salmoides and Cyprinus carpio dominated, while in streams and rivers, the assemblage consisted mainly of Hemibrycon caucanus and Trichomycterus sp. There were no statistical differences in the assemblages according to the climatic period. We observed that physicochemical variables such as oxygen and transparency are important for the distribution of non-native species in reservoirs, and for species distributed in rivers and streams, the conductivity was the most influential variable. The information provided in this study will serve as a basis for fish conservation management in the Andes., El desarrollo de producción hidro-energética al norte de los Andes de Sudamérica se ha centrado en la cuenca Magdalena. Para esta cuenca se reporta que el 68 % de las especies de peces son endémicas y no se han estudiado los efectos que producen estas estructuras sobre sus ensamblajes en los ríos de alta montaña. Este trabajo responde preguntas asociadas a las características que describen el ensamblaje de peces y la influencia que ejercen algunas variables ambientales sobre su distribución en el transcurso de los periodos hidrológicos de sequía y lluvias en el área de influencia de dos embalses. Se capturaron siete especies de peces, cuatro de ellas no nativas de la cuenca. No se encontraron diferencias significativas de las abundancias entre los sistemas acuáticos y entre la temporalidad climática. La riqueza fue mayor en las quebradas y ríos. Los ensamblajes cambiaron según el sistema acuático, en embalses dominaron las especies no nativas Micropterus salmoides y Cyprinus carpio mientras que en las quebradas y ríos el ensamblaje estuvo conformado principalmente por Hemibrycon caucanus y Trichomycterus sp. Los ensamblajes no presentaron diferencias estadísticas entre periodos climáticos. Por otra parte, observamos que variables fisicoquímicas como el oxígeno y la transparencia, son importantes para la distribución de las especies no nativas en los embalses, y para las especies que se distribuyen en ríos y quebradas, la conductividad fue la variable más influyente. La información proporcionada en este estudio servirá de base para la gestión de la conservación de peces en los Andes.

The development of hydropower production in the north of the Andes of South America has focused on the Magdalena basin. For this basin, it is reported that 68 % of the fish species are endemic and the effects that these structures produce on their assemblages in high mountain rivers have not been studied. This work answers the questions associated with the characteristics that describe the fish assemblage and the influence that some environmental variables influence on their distribution during the dry and rainy hydrological periods in the area of influence of two reservoirs. Seven fish species were caught, four of these are not native from the basin. No significant differences in abundances were found between aquatic systems and between climatic seasonality. The richness was higher in the streams and rivers. The assemblages changed according to the aquatic system; in reservoirs, the non-native species Micropterus salmoides and Cyprinus carpio dominated, while in streams and rivers, the assemblage consisted mainly of Hemibrycon caucanus and Trichomycterus sp. There were no statistical differences in the assemblages according to the climatic period. We observed that physicochemical variables such as oxygen and transparency are important for the distribution of non-native species in reservoirs, and for species distributed in rivers and streams, the conductivity was the most influential variable. The information provided in this study will serve as a basis for fish conservation management in the Andes., El desarrollo de producción hidro-energética al norte de los Andes de Sudamérica se ha centrado en la cuenca Magdalena. Para esta cuenca se reporta que el 68 % de las especies de peces son endémicas y no se han estudiado los efectos que producen estas estructuras sobre sus ensamblajes en los ríos de alta montaña. Este trabajo responde preguntas asociadas a las características que describen el ensamblaje de peces y la influencia que ejercen algunas variables ambientales sobre su distribución en el transcurso de los periodos hidrológicos de sequía y lluvias en el área de influencia de dos embalses. Se capturaron siete especies de peces, cuatro de ellas no nativas de la cuenca. No se encontraron diferencias significativas de las abundancias entre los sistemas acuáticos y entre la temporalidad climática. La riqueza fue mayor en las quebradas y ríos. Los ensamblajes cambiaron según el sistema acuático, en embalses dominaron las especies no nativas Micropterus salmoides y Cyprinus carpio mientras que en las quebradas y ríos el ensamblaje estuvo conformado principalmente por Hemibrycon caucanus y Trichomycterus sp. Los ensamblajes no presentaron diferencias estadísticas entre periodos climáticos. Por otra parte, observamos que variables fisicoquímicas como el oxígeno y la transparencia, son importantes para la distribución de las especies no nativas en los embalses, y para las especies que se distribuyen en ríos y quebradas, la conductividad fue la variable más influyente. La información proporcionada en este estudio servirá de base para la gestión de la conservación de peces en los Andes.

The inventories of fish fauna through the elevation interval in Andean rivers are tools to generate conservation strategies in the region, therefore the completeness of these inventories is essential to take sound decisions. The material deposited in five biological collections, and that collected in three explorations carried out in years 2014, 015, and 2016 in 64 localities that drain into the Magdalena River basin was examined. The richness consisted of 115 fish species. We found that the rate of decrease in the number of species was 54 per 900 m. of elevation. Using a species prediction model, we showed that the total number of species was only recorded in the 300-600 m. interval and in the high Andean zone. This suggests that a greater sampling effort is required to obtain a sufficient representation of the estimated real richness for each the elevation intervals evaluated. Additionally, different threats on the water bodies were detected in the elevation intervals, such as extensive cattle ranching and agriculture, unregulated mineral extraction, hydroelectric power generation, as well as the use of fish as a protein resource, including the farming of introduced species. As the modification of habitats continues without adequate planning, there is a risk of affecting the richness and distribution of species in the basin, therefore, it is important to know their ecological aspects, which will allow to propose recommendations and find opportunities for their conservation., Los inventarios de riqueza íctica a lo largo del intervalo de elevación de los ríos andinos son herramientas para generar estrategias de conservación en la región, así que su exhaustividad es definitiva para tomar decisiones acertadas. Se revisó el material depositado en cinco colecciones biológicas, y también el recolectado en tres exploraciones realizadas en los años 2014, 2015 y 2016 en 64 localidades que drenan hacia la cuenca hidrográfica del río Magdalena. La riqueza estuvo conformada por 115 especies de peces. Se encontró que la tasa de disminución en el número de especies fue de 54 por cada 900 m. de elevación. Mediante un modelo de predicción de especies demostramos que solo se alcanzó a registrar el número total de especies en el intervalo de 300-600 m. y en la zona altoandina. Esto sugiere que es necesario un mayor esfuerzo de muestreo para obtener una suficiente representación de la riqueza real estimada para cada intervalo de elevación. Adicionalmente, se detectaron diferentes amenazas sobre los cuerpos de agua en los intervalos de elevación, tales como ganadería extensiva y agricultura, extracción de minerales sin regulaciones, generación de energía hidroeléctrica, así como el uso de los peces como recurso proteico, incluyendo el cultivo de especies introducidas. A medida que la modificación de hábitats continúe sin una adecuada planeación, se corre el riesgo de afectar la riqueza y distribución de especies de peces en la cuenca, por lo tanto, es importante conocer sus aspectos ecológicos, que permitirán proponer recomendaciones y oportunidades para su conservación.

The development of hydropower production in the north of the Andes of South America has focused on the Magdalena basin. For this basin, it is reported that 68 % of the fish species are endemic and the effects that these structures produce on their assemblages in high mountain rivers have not been studied. This work answers the questions associated with the characteristics that describe the fish assemblage and the influence that some environmental variables influence on their distribution during the dry and rainy hydrological periods in the area of influence of two reservoirs. Seven fish species were caught, four of these are not native from the basin. No significant differences in abundances were found between aquatic systems and between climatic seasonality. The richness was higher in the streams and rivers. The assemblages changed according to the aquatic system; in reservoirs, the non-native species Micropterus salmoides and Cyprinus carpio dominated, while in streams and rivers, the assemblage consisted mainly of Hemibrycon caucanus and Trichomycterus sp. There were no statistical differences in the assemblages according to the climatic period. We observed that physicochemical variables such as oxygen and transparency are important for the distribution of non-native species in reservoirs, and for species distributed in rivers and streams, the conductivity was the most influential variable. The information provided in this study will serve as a basis for fish conservation management in the Andes., El desarrollo de producción hidro-energética al norte de los Andes de Sudamérica se ha centrado en la cuenca Magdalena. Para esta cuenca se reporta que el 68 % de las especies de peces son endémicas y no se han estudiado los efectos que producen estas estructuras sobre sus ensamblajes en los ríos de alta montaña. Este trabajo responde preguntas asociadas a las características que describen el ensamblaje de peces y la influencia que ejercen algunas variables ambientales sobre su distribución en el transcurso de los periodos hidrológicos de sequía y lluvias en el área de influencia de dos embalses. Se capturaron siete especies de peces, cuatro de ellas no nativas de la cuenca. No se encontraron diferencias significativas de las abundancias entre los sistemas acuáticos y entre la temporalidad climática. La riqueza fue mayor en las quebradas y ríos. Los ensamblajes cambiaron según el sistema acuático, en embalses dominaron las especies no nativas Micropterus salmoides y Cyprinus carpio mientras que en las quebradas y ríos el ensamblaje estuvo conformado principalmente por Hemibrycon caucanus y Trichomycterus sp. Los ensamblajes no presentaron diferencias estadísticas entre periodos climáticos. Por otra parte, observamos que variables fisicoquímicas como el oxígeno y la transparencia, son importantes para la distribución de las especies no nativas en los embalses, y para las especies que se distribuyen en ríos y quebradas, la conductividad fue la variable más influyente. La información proporcionada en este estudio servirá de base para la gestión de la conservación de peces en los Andes.

The inventories of fish fauna through the elevation interval in Andean rivers are tools to generate conservation strategies in the region, therefore the completeness of these inventories is essential to take sound decisions. The material deposited in five biological collections, and that collected in three explorations carried out in years 2014, 015, and 2016 in 64 localities that drain into the Magdalena River basin was examined. The richness consisted of 115 fish species. We found that the rate of decrease in the number of species was 54 per 900 m. of elevation. Using a species prediction model, we showed that the total number of species was only recorded in the 300-600 m. interval and in the high Andean zone. This suggests that a greater sampling effort is required to obtain a sufficient representation of the estimated real richness for each the elevation intervals evaluated. Additionally, different threats on the water bodies were detected in the elevation intervals, such as extensive cattle ranching and agriculture, unregulated mineral extraction, hydroelectric power generation, as well as the use of fish as a protein resource, including the farming of introduced species. As the modification of habitats continues without adequate planning, there is a risk of affecting the richness and distribution of species in the basin, therefore, it is important to know their ecological aspects, which will allow to propose recommendations and find opportunities for their conservation., Los inventarios de riqueza íctica a lo largo del intervalo de elevación de los ríos andinos son herramientas para generar estrategias de conservación en la región, así que su exhaustividad es definitiva para tomar decisiones acertadas. Se revisó el material depositado en cinco colecciones biológicas, y también el recolectado en tres exploraciones realizadas en los años 2014, 2015 y 2016 en 64 localidades que drenan hacia la cuenca hidrográfica del río Magdalena. La riqueza estuvo conformada por 115 especies de peces. Se encontró que la tasa de disminución en el número de especies fue de 54 por cada 900 m. de elevación. Mediante un modelo de predicción de especies demostramos que solo se alcanzó a registrar el número total de especies en el intervalo de 300-600 m. y en la zona altoandina. Esto sugiere que es necesario un mayor esfuerzo de muestreo para obtener una suficiente representación de la riqueza real estimada para cada intervalo de elevación. Adicionalmente, se detectaron diferentes amenazas sobre los cuerpos de agua en los intervalos de elevación, tales como ganadería extensiva y agricultura, extracción de minerales sin regulaciones, generación de energía hidroeléctrica, así como el uso de los peces como recurso proteico, incluyendo el cultivo de especies introducidas. A medida que la modificación de hábitats continúe sin una adecuada planeación, se corre el riesgo de afectar la riqueza y distribución de especies de peces en la cuenca, por lo tanto, es importante conocer sus aspectos ecológicos, que permitirán proponer recomendaciones y oportunidades para su conservación.

The development of hydropower production in the north of the Andes of South America has focused on the Magdalena basin. For this basin, it is reported that 68 % of the fish species are endemic and the effects that these structures produce on their assemblages in high mountain rivers have not been studied. This work answers the questions associated with the characteristics that describe the fish assemblage and the influence that some environmental variables influence on their distribution during the dry and rainy hydrological periods in the area of influence of two reservoirs. Seven fish species were caught, four of these are not native from the basin. No significant differences in abundances were found between aquatic systems and between climatic seasonality. The richness was higher in the streams and rivers. The assemblages changed according to the aquatic system; in reservoirs, the non-native species Micropterus salmoides and Cyprinus carpio dominated, while in streams and rivers, the assemblage consisted mainly of Hemibrycon caucanus and Trichomycterus sp. There were no statistical differences in the assemblages according to the climatic period. We observed that physicochemical variables such as oxygen and transparency are important for the distribution of non-native species in reservoirs, and for species distributed in rivers and streams, the conductivity was the most influential variable. The information provided in this study will serve as a basis for fish conservation management in the Andes., El desarrollo de producción hidro-energética al norte de los Andes de Sudamérica se ha centrado en la cuenca Magdalena. Para esta cuenca se reporta que el 68 % de las especies de peces son endémicas y no se han estudiado los efectos que producen estas estructuras sobre sus ensamblajes en los ríos de alta montaña. Este trabajo responde preguntas asociadas a las características que describen el ensamblaje de peces y la influencia que ejercen algunas variables ambientales sobre su distribución en el transcurso de los periodos hidrológicos de sequía y lluvias en el área de influencia de dos embalses. Se capturaron siete especies de peces, cuatro de ellas no nativas de la cuenca. No se encontraron diferencias significativas de las abundancias entre los sistemas acuáticos y entre la temporalidad climática. La riqueza fue mayor en las quebradas y ríos. Los ensamblajes cambiaron según el sistema acuático, en embalses dominaron las especies no nativas Micropterus salmoides y Cyprinus carpio mientras que en las quebradas y ríos el ensamblaje estuvo conformado principalmente por Hemibrycon caucanus y Trichomycterus sp. Los ensamblajes no presentaron diferencias estadísticas entre periodos climáticos. Por otra parte, observamos que variables fisicoquímicas como el oxígeno y la transparencia, son importantes para la distribución de las especies no nativas en los embalses, y para las especies que se distribuyen en ríos y quebradas, la conductividad fue la variable más influyente. La información proporcionada en este estudio servirá de base para la gestión de la conservación de peces en los Andes.

Tambaqui or cachama (Colossoma macropomum) is one of the most important neo-tropical freshwater fish used for aquaculture in South America, and its production is concentrated at low latitudes (close to the Equator, 0°), where the water tempera-ture is warm. Therefore, understanding how selection shapes genetic variations and structure in farmed populations is of paramount importance in evolutionary biology. High- throughput sequencing to generate genome-wide data for fish species allows for elucidating the genomic basis of adaptation to local or farmed conditions and un-covering genes that control the phenotypes of interest. The present study aimed to detect genomic selection signatures and analyze the genetic variability in farmed pop-ulations of tambaqui in South America using single- nucleotide polymorphism (SNP) markers obtained with double-digest restriction site-associated DNA sequencing. Initially, 199 samples of tambaqui farmed populations from different locations (lo-cated in Brazil, Colombia, and Peru), a wild population (Amazon River, Brazil), and the base population of a breeding program (Aquaculture Center, CAUNESP, Jaboticabal, SP, Brazil) were genotyped. Observed and expected heterozygosity was 0.231–0.350 and 0.288– 0.360, respectively. Significant genetic differentiation was observed using global FST analyses of SNP loci (FST = 0.064, p< 0.050). Farmed populations from Colombia and Peru that differentiated from the Brazilian populations formed distinct groups. Several regions, particularly those harboring the genes of significance to aq-uaculture, were identified to be under positive selection, suggesting local adapta-tion to stress under different farming conditions and management practices. Studies aimed at improving the knowledge of genomics of tambaqui farmed populations are essential for aquaculture to gain deeper insights into the evolutionary history of these fish and provide resources for the establishment of breeding programs

Pseudoplatystoma punctifer is an Amazonian catfish highly appreciated for its high flesh quality, size, and commercial value. Its aquaculture is pursued to satisfy the demands of an increasing population in the region. However, knowledge of the nutritional needs during the early life stages is necessary for improving growth and reducing the incidence of cannibalism, factors that limit the success of its commercial farming. This study aimed at evaluating the influence of four diets containing different protein and lipid levels (30:15, 30:10, 45:15, or 45:10 in %) in the digestive physiology and performance of early juveniles. The results showed that the dietary protein:lipid as well as carbohydrate levels and ratios influenced differently the whole-body proximate composition, the digestive physiology and development, and hence growth and survival. The 45:15 diet promoted the best growth, survival, and the most rapid development of the digestive system, as shown at histological (higher number of hepatocytes, goblet cells in the anterior intestine and enterocytes in all intestinal portions, and longer folds in the posterior intestine), molecular (highest amylase, lipoprotein lipase, phospholipase, trypsinogen, and pepsinogen gene expression), and biochemical (highest lipase and pepsin activities and higher alkaline phosphatase:leucine alanine peptidase activity ratio) levels. Lipids were favored over carbohydrates as source of energy, with lipids promoting a protein-sparing effect at adequate energy:protein ratio. Carbohydrate content higher than 25% was excessive for this species, leading to unbalanced lipid metabolism and fat deposition in the liver.

The inventories of fish fauna through the elevation interval in Andean rivers are tools to generate conservation strategies in the region, therefore the completeness of these inventories is essential to take sound decisions. The material deposited in five biological collections, and that collected in three explorations carried out in years 2014, 2015, and 2016 in 64 localities that drain into the Magdalena River basin was examined. The richness consisted of 115 fish species. We found that the rate of decrease in the number of species was 54 per 900 m. of elevation. Using a species prediction model, we showed that the total number of species was only recorded in the 300-600 m. interval and in the high Andean zone. This suggests that a greater sampling effort is required to obtain a sufficient representation of the estimated real richness for each the elevation intervals evaluated. Additionally, different threats on the water bodies were detected in the elevation intervals, such as extensive cattle ranching and agriculture, unregulated mineral extraction, hydroelectric power generation, as well as the use of fish as a protein resource, including the farming of introduced species. As the modification of habitats continues without adequate planning, there is a risk of affecting the richness and distribution of species in the basin, therefore, it is important to know their ecological aspects, which will allow to propose recommendations and find opportunities for their conservation., Los inventarios de riqueza íctica a lo largo del intervalo de elevación de los ríos andinos son herramientas para generar estrategias de conservación en la región, así que su exhaustividad es definitiva para tomar decisiones acertadas. Se revisó el material depositado en cinco colecciones biológicas, y también el recolectado en tres exploraciones realizadas en los años 2014, 2015 y 2016 en 64 localidades que drenan hacia la cuenca hidrográfica del río Magdalena. La riqueza estuvo conformada por 115 especies de peces. Se encontró que la tasa de disminución en el número de especies fue de 54 por cada 900 m. de elevación. Mediante un modelo de predicción de especies demostramos que solo se alcanzó a registrar el número total de especies en el intervalo de 300-600 m. y en la zona altoandina. Esto sugiere que es necesario un mayor esfuerzo de muestreo para obtener una suficiente representación de la riqueza real estimada para cada intervalo de elevación. Adicionalmente, se detectaron diferentes amenazas sobre los cuerpos de agua en los intervalos de elevación, tales como ganadería extensiva y agricultura, extracción de minerales sin regulaciones, generación de energía hidroeléctrica, así como el uso de los peces como recurso proteico, incluyendo el cultivo de especies introducidas. A medida que la modificación de hábitats continúe sin una adecuada planeación, se corre el riesgo de afectar la riqueza y distribución de especies de peces en la cuenca, por lo tanto, es importante conocer sus aspectos ecológicos, que permitirán proponer recomendaciones y oportunidades para su conservación.

Pseudoplatystoma punctifer is an Amazonian catfish highly appreciated for its high flesh quality, size, and commercial value. Its aquaculture is pursued to satisfy the demands of an increasing population in the region. However, knowledge of the nutritional needs during the early life stages is necessary for improving growth and reducing the incidence of cannibalism, factors that limit the success of its commercial farming. This study aimed at evaluating the influence of four diets containing different protein and lipid levels (30:15, 30:10, 45:15, or 45:10 in %) in the digestive physiology and performance of early juveniles. The results showed that the dietary protein:lipid as well as carbohydrate levels and ratios influenced differently the whole-body proximate composition, the digestive physiology and development, and hence growth and survival. The 45:15 diet promoted the best growth, survival, and the most rapid development of the digestive system, as shown at histological (higher number of hepatocytes, goblet cells in the anterior intestine and enterocytes in all intestinal portions, and longer folds in the posterior intestine), molecular (highest amylase, lipoprotein lipase, phospholipase, trypsinogen, and pepsinogen gene expression), and biochemical (highest lipase and pepsin activities and higher alkaline phosphatase:leucine alanine peptidase activity ratio) levels. Lipids were favored over carbohydrates as source of energy, with lipids promoting a protein-sparing effect at adequate energy:protein ratio. Carbohydrate content higher than 25% was excessive for this species, leading to unbalanced lipid metabolism and fat deposition in the liver.

Eukaryotic genomes contain large amounts of repetitive DNA sequences, such as tandemly repeated satelliteDNAs (satDNAs). These sequences are highly dynamic and tend to begenus- or species-specific due to their particular evolutionary pathways, although there are few unusual cases of conserved satDNAs over long periods of time. Here, we used multiple approaches to reveal that an satDNA named CharSat01-52 originated in the last common ancestor of Characoidei fish, a superfamily within the Characiformes order, similar to 140-78Ma, whereas its nucleotide composition has remained considerably conserved in several taxa. We show that 14 distantly related species within Characoidei share the presence of this satDNA, which is highly amplified and clustered in subtelomeric regions in a single species (Characidiumgomesi), while remained organized as small clusters in all the other species. Defying predictions of the molecular drive of satellite evolution, CharSat01-52 shows similar values of intra- and interspecific divergence. Although we did not provide evidence for a specific functional role of CharSat01-52, its transcriptional activity was demonstrated in different species. In addition, we identified short tandem arrays of CharSat01-52 embedded within single-molecule real-time long reads of Astyanax paranae (536 bp-3.1 kb) and A. mexicanus (501 bp-3.9 kb). Such arrays consisted of head-to-tail repeats and could b e found interspersed with other sequences, inverted sequences, or neighbored by other satellites. Our results provide a detailed characterization of an old and conserved satDNA, challenging general predictions of satDNA evolution.

Eukaryotic genomes contain large amounts of repetitive DNA sequences, such as tandemly repeated satelliteDNAs (satDNAs). These sequences are highly dynamic and tend to begenus- or species-specific due to their particular evolutionary pathways, although there are few unusual cases of conserved satDNAs over long periods of time. Here, we used multiple approaches to reveal that an satDNA named CharSat01-52 originated in the last common ancestor of Characoidei fish, a superfamily within the Characiformes order, similar to 140-78Ma, whereas its nucleotide composition has remained considerably conserved in several taxa. We show that 14 distantly related species within Characoidei share the presence of this satDNA, which is highly amplified and clustered in subtelomeric regions in a single species (Characidiumgomesi), while remained organized as small clusters in all the other species. Defying predictions of the molecular drive of satellite evolution, CharSat01-52 shows similar values of intra- and interspecific divergence. Although we did not provide evidence for a specific functional role of CharSat01-52, its transcriptional activity was demonstrated in different species. In addition, we identified short tandem arrays of CharSat01-52 embedded within single-molecule real-time long reads of Astyanax paranae (536 bp-3.1 kb) and A. mexicanus (501 bp-3.9 kb). Such arrays consisted of head-to-tail repeats and could b e found interspersed with other sequences, inverted sequences, or neighbored by other satellites. Our results provide a detailed characterization of an old and conserved satDNA, challenging general predictions of satDNA evolution.

Eukaryotic genomes contain large amounts of repetitive DNA sequences, such as tandemly repeated satelliteDNAs (satDNAs). These sequences are highly dynamic and tend to begenus- or species-specific due to their particular evolutionary pathways, although there are few unusual cases of conserved satDNAs over long periods of time. Here, we used multiple approaches to reveal that an satDNA named CharSat01-52 originated in the last common ancestor of Characoidei fish, a superfamily within the Characiformes order, similar to 140-78Ma, whereas its nucleotide composition has remained considerably conserved in several taxa. We show that 14 distantly related species within Characoidei share the presence of this satDNA, which is highly amplified and clustered in subtelomeric regions in a single species (Characidiumgomesi), while remained organized as small clusters in all the other species. Defying predictions of the molecular drive of satellite evolution, CharSat01-52 shows similar values of intra- and interspecific divergence. Although we did not provide evidence for a specific functional role of CharSat01-52, its transcriptional activity was demonstrated in different species. In addition, we identified short tandem arrays of CharSat01-52 embedded within single-molecule real-time long reads of Astyanax paranae (536 bp-3.1 kb) and A. mexicanus (501 bp-3.9 kb). Such arrays consisted of head-to-tail repeats and could b e found interspersed with other sequences, inverted sequences, or neighbored by other satellites. Our results provide a detailed characterization of an old and conserved satDNA, challenging general predictions of satDNA evolution.

Eukaryotic genomes contain large amounts of repetitive DNA sequences, such as tandemly repeated satelliteDNAs (satDNAs). These sequences are highly dynamic and tend to begenus- or species-specific due to their particular evolutionary pathways, although there are few unusual cases of conserved satDNAs over long periods of time. Here, we used multiple approaches to reveal that an satDNA named CharSat01-52 originated in the last common ancestor of Characoidei fish, a superfamily within the Characiformes order, similar to 140-78Ma, whereas its nucleotide composition has remained considerably conserved in several taxa. We show that 14 distantly related species within Characoidei share the presence of this satDNA, which is highly amplified and clustered in subtelomeric regions in a single species (Characidiumgomesi), while remained organized as small clusters in all the other species. Defying predictions of the molecular drive of satellite evolution, CharSat01-52 shows similar values of intra- and interspecific divergence. Although we did not provide evidence for a specific functional role of CharSat01-52, its transcriptional activity was demonstrated in different species. In addition, we identified short tandem arrays of CharSat01-52 embedded within single-molecule real-time long reads of Astyanax paranae (536 bp-3.1 kb) and A. mexicanus (501 bp-3.9 kb). Such arrays consisted of head-to-tail repeats and could b e found interspersed with other sequences, inverted sequences, or neighbored by other satellites. Our results provide a detailed characterization of an old and conserved satDNA, challenging general predictions of satDNA evolution.

Pseudoplatystoma punctifer is an Amazonian catfish highly appreciated for its high flesh quality, size, and commercial value. Its aquaculture is pursued to satisfy the demands of an increasing population in the region. However, knowledge of the nutritional needs during the early life stages is necessary for improving growth and reducing the incidence of cannibalism, factors that limit the success of its commercial farming. This study aimed at evaluating the influence of four diets containing different protein and lipid levels (30:15, 30:10, 45:15, or 45:10 in %) in the digestive physiology and performance of early juveniles. The results showed that the dietary protein:lipid as well as carbohydrate levels and ratios influenced differently the whole-body proximate composition, the digestive physiology and development, and hence growth and survival. The 45:15 diet promoted the best growth, survival, and the most rapid development of the digestive system, as shown at histological (higher number of hepatocytes, goblet cells in the anterior intestine and enterocytes in all intestinal portions, and longer folds in the posterior intestine), molecular (highest amylase, lipoprotein lipase, phospholipase, trypsinogen, and pepsinogen gene expression), and biochemical (highest lipase and pepsin activities and higher alkaline phosphatase:leucine alanine peptidase activity ratio) levels. Lipids were favored over carbohydrates as source of energy, with lipids promoting a protein-sparing effect at adequate energy:protein ratio. Carbohydrate content higher than 25% was excessive for this species, leading to unbalanced lipid metabolism and fat deposition in the liver.

Eukaryotic genomes contain large amounts of repetitive DNA sequences, such as tandemly repeated satelliteDNAs (satDNAs). These sequences are highly dynamic and tend to begenus- or species-specific due to their particular evolutionary pathways, although there are few unusual cases of conserved satDNAs over long periods of time. Here, we used multiple approaches to reveal that an satDNA named CharSat01-52 originated in the last common ancestor of Characoidei fish, a superfamily within the Characiformes order, similar to 140-78Ma, whereas its nucleotide composition has remained considerably conserved in several taxa. We show that 14 distantly related species within Characoidei share the presence of this satDNA, which is highly amplified and clustered in subtelomeric regions in a single species (Characidiumgomesi), while remained organized as small clusters in all the other species. Defying predictions of the molecular drive of satellite evolution, CharSat01-52 shows similar values of intra- and interspecific divergence. Although we did not provide evidence for a specific functional role of CharSat01-52, its transcriptional activity was demonstrated in different species. In addition, we identified short tandem arrays of CharSat01-52 embedded within single-molecule real-time long reads of Astyanax paranae (536 bp-3.1 kb) and A. mexicanus (501 bp-3.9 kb). Such arrays consisted of head-to-tail repeats and could b e found interspersed with other sequences, inverted sequences, or neighbored by other satellites. Our results provide a detailed characterization of an old and conserved satDNA, challenging general predictions of satDNA evolution.

The lambari, Astyanax altiparanae, exhibits a great potential for aquaculture due to its omnivory, rapid growth and ease captive production. Despite of fish lipid metabolism being directly related to the dietary lipid consumed, which may lead to changes in fish growth, nothing much have been established regarding the lipid sources that can be applied in A. altiparanae captive production. Thus, this present research was conducted aiming to evaluate the growth performance and whole body composition of A. altiparanae fed with lipid sources of plant and/or animal origins. Were used a Completely Randomized design experiment with five treatments. The treatments consisted of isoproteic and isoenergetic diets, containing the following lipid sources: T1: linseed, chia and sunflower oils; T2: linseed and corn oils; T3: linseed, chia, corn and sunflower oils; T4: sunflower, corn and fish oils; T5: linseed, chia, sunflower, corn oils and bovine fat. Each treatment was replicated six times, where the experimental units consists of 10 fishes (averaged weight: 4.0 + 0.5 g) placed in an aquarium containing 80L of dechlorinated water. Were compared the growth performance parameters among the treatments by applying an one-way analysis of variance (ANOVA) at 5% significance (P < 0.05). The results revealed that both growth performance and whole body composition of A. altiparanae were not affected by the lipid source, which indicate that these fishes can efficiently use both vegetable lipid sources as well as mixtures of vegetable and animal lipid sources without any growth disadvantages., El lambari, Astyanax altiparanae, exhibe un gran potencial para la acuicultura debido a su crecimiento omnívoro, rápido y fácil de cautiverio. A pesar de que el metabolismo de los lípidos en los peces está directamente relacionado con los lípidos de la dieta, lo que puede conducir a cambios en el crecimiento de los peces, no se ha establecido mucho sobre las fuentes de lípidos que se pueden aplicar en la producción en cautiverio de A. altiparanae. Por lo tanto, esta investigación se realizó con el objetivo de evaluar el rendimiento del crecimiento y la composición del cuerpo de A. altiparanae alimentados con fuentes de lípidos de origen vegetal y animal. Se utilizó un experimento de diseño completamente al azar con cinco tratamientos. Los tratamientos consistieron en dietas isoproteicas e isoenergéticas, que contenían las siguientes fuentes de lípidos: T1: aceites de linaza, chía y girasol; T2: aceites de linaza y maíz; T3: aceites de linaza, chía, maíz y girasol; T4: girasol, maíz y aceites de pescado; T5: linaza, chía, girasol, aceites de maíz y grasa bovina. Cada tratamiento se repitió seis veces, las unidades experimentales consisten en 10 peces (peso promedio: 4.0 + 0.5 g) colocados en un acuario que contiene 80 litros de agua desclorada. Se compararon los parámetros de rendimiento de crecimiento entre los tratamientos mediante la aplicación de un análisis de varianza unidireccional (ANOVA) con una significancia del 5% (P <0.05). Los resultados revelaron que tanto el rendimiento del crecimiento como la composición del cuerpo de A. altiparanae no se vieron afectados por la fuente de lípidos, lo que indica que estos peces pueden usar eficientemente tanto fuentes de lípidos vegetales como mezclas de fuentes de lípidos vegetales y animales sin ninguna desventaja de crecimiento

The lambari, Astyanax altiparanae, exhibits a great potential for aquaculture due to its omnivory, rapid growth and ease captive production. Despite of fish lipid metabolism being directly related to the dietary lipid consumed, which may lead to changes in fish growth, nothing much have been established regarding the lipid sources that can be applied in A. altiparanae captive production. Thus, this present research was conducted aiming to evaluate the growth performance and whole body composition of A. altiparanae fed with lipid sources of plant and/or animal origins. Were used a Completely Randomized design experiment with five treatments. The treatments consisted of isoproteic and isoenergetic diets, containing the following lipid sources: T1: linseed, chia and sunflower oils; T2: linseed and corn oils; T3: linseed, chia, corn and sunflower oils; T4: sunflower, corn and fish oils; T5: linseed, chia, sunflower, corn oils and bovine fat. Each treatment was replicated six times, where the experimental units consists of 10 fishes (averaged weight: 4.0 + 0.5 g) placed in an aquarium containing 80L of dechlorinated water. Were compared the growth performance parameters among the treatments by applying an one-way analysis of variance (ANOVA) at 5% significance (P < 0.05). The results revealed that both growth performance and whole body composition of A. altiparanae were not affected by the lipid source, which indicate that these fishes can efficiently use both vegetable lipid sources as well as mixtures of vegetable and animal lipid sources without any growth disadvantages., El lambari, Astyanax altiparanae, exhibe un gran potencial para la acuicultura debido a su crecimiento omnívoro, rápido y fácil de cautiverio. A pesar de que el metabolismo de los lípidos en los peces está directamente relacionado con los lípidos de la dieta, lo que puede conducir a cambios en el crecimiento de los peces, no se ha establecido mucho sobre las fuentes de lípidos que se pueden aplicar en la producción en cautiverio de A. altiparanae. Por lo tanto, esta investigación se realizó con el objetivo de evaluar el rendimiento del crecimiento y la composición del cuerpo de A. altiparanae alimentados con fuentes de lípidos de origen vegetal y animal. Se utilizó un experimento de diseño completamente al azar con cinco tratamientos. Los tratamientos consistieron en dietas isoproteicas e isoenergéticas, que contenían las siguientes fuentes de lípidos: T1: aceites de linaza, chía y girasol; T2: aceites de linaza y maíz; T3: aceites de linaza, chía, maíz y girasol; T4: girasol, maíz y aceites de pescado; T5: linaza, chía, girasol, aceites de maíz y grasa bovina. Cada tratamiento se repitió seis veces, las unidades experimentales consisten en 10 peces (peso promedio: 4.0 + 0.5 g) colocados en un acuario que contiene 80 litros de agua desclorada. Se compararon los parámetros de rendimiento de crecimiento entre los tratamientos mediante la aplicación de un análisis de varianza unidireccional (ANOVA) con una significancia del 5% (P <0.05). Los resultados revelaron que tanto el rendimiento del crecimiento como la composición del cuerpo de A. altiparanae no se vieron afectados por la fuente de lípidos, lo que indica que estos peces pueden usar eficientemente tanto fuentes de lípidos vegetales como mezclas de fuentes de lípidos vegetales y animales sin ninguna desventaja de crecimiento

The physical habitat simulation sub-routine of the Instream Flow Incremental Methodology (IFIM) uses hydraulic modeling and suitability indices of target fish species to predict how differences in-stream flows affect the microhabitat occupation by fish species. This habitat modelling approach was adopted to assess the ecological effects of running flows on three neotropical fish species of different orders (Bryconamericus ornaticeps, Ancistrus multispinis and Geophagus brasiliensis).The study encompassed two reaches of an Atlantic Forest stream in Southeastern Brazil where topographic and hydraulic (depth, velocity and type of substrate) characteristics were measured to implement one-dimensional hydraulic simulation. Sub aquatic observation of fish was performed to collect data on microhabitat use and these data were used to develop habitat suitability curves that were used in the habitat simulation to obtain the habitat suitability index (HSI) and weighted usable area (WUA) versus flow curves. Upon these curves minimum and optimum environmental flows for the target fish species were proposed. Bryconamericus ornaticeps and A. multispinis selected microhabitats around 0.6 m depth, whereas G. brasiliensis showed a wider suitable range (0.35-0.9 m). All the three species were mainly observed in microhabitat with low flow velocity (0.1 m/s). Bryconamericus ornaticeps selected more frequently coarse substrate (e.g. boulders) but it appeared also over sandy substrate, whereas A. multispinis and G. brasiliensis selected preferably boulders. The range of 0.65-0.85 m3/s was found as the optimum to meet the needs of the three fish species. Our results agree with the necessary objective information to perform grounded management actions in the frame of a management program aiming at ecosystem conservation. Thereby it can be considered a successful pilot study in environmental flow assessment in an Atlantic Forest stream of Brazil.

In hypoxia, gray mullet surface to ventilate well-oxygenated water in contact with air, an adaptive response known as aquatic surface respiration (ASR). Reflex control of ASR and its behavioral modulation by perceived threat of aerial predation and turbid water were studied on mullet in a partly sheltered aquarium with free surface access. Injections of sodium cyanide (NaCN) into either the bloodstream ( internal) or ventilatory water stream ( external) revealed that ASR, hypoxic bradycardia, and branchial hyperventilation were stimulated by chemoreceptors sensitive to both systemic and water O-2 levels. Sight of a model avian predator elicited bradycardia and hypoventilation, a fear response that inhibited reflex hyperventilation following external NaCN. The time lag to initiation of ASR following NaCN increased, but response intensity ( number of events, time at the surface) was unchanged. Mullet, however, modified their behavior to surface under shelter or near the aquarium edges. Turbid water abolished the fear response and effects of the predator on gill ventilation and timing of ASR following external NaCN, presumably because of reduced visibility. However, in turbidity, mullet consistently performed ASR under shelter or near the aquarium edges. These adaptive modulations of ASR behavior would allow mullet to retain advantages of the chemoreflex when threatened by avian predators or when unable to perceive potential threats in turbidity.

In hypoxia, gray mullet surface to ventilate well-oxygenated water in contact with air, an adaptive response known as aquatic surface respiration (ASR). Reflex control of ASR and its behavioral modulation by perceived threat of aerial predation and turbid water were studied on mullet in a partly sheltered aquarium with free surface access. Injections of sodium cyanide (NaCN) into either the bloodstream ( internal) or ventilatory water stream ( external) revealed that ASR, hypoxic bradycardia, and branchial hyperventilation were stimulated by chemoreceptors sensitive to both systemic and water O-2 levels. Sight of a model avian predator elicited bradycardia and hypoventilation, a fear response that inhibited reflex hyperventilation following external NaCN. The time lag to initiation of ASR following NaCN increased, but response intensity ( number of events, time at the surface) was unchanged. Mullet, however, modified their behavior to surface under shelter or near the aquarium edges. Turbid water abolished the fear response and effects of the predator on gill ventilation and timing of ASR following external NaCN, presumably because of reduced visibility. However, in turbidity, mullet consistently performed ASR under shelter or near the aquarium edges. These adaptive modulations of ASR behavior would allow mullet to retain advantages of the chemoreflex when threatened by avian predators or when unable to perceive potential threats in turbidity.

In hypoxia, gray mullet surface to ventilate well-oxygenated water in contact with air, an adaptive response known as aquatic surface respiration (ASR). Reflex control of ASR and its behavioral modulation by perceived threat of aerial predation and turbid water were studied on mullet in a partly sheltered aquarium with free surface access. Injections of sodium cyanide (NaCN) into either the bloodstream ( internal) or ventilatory water stream ( external) revealed that ASR, hypoxic bradycardia, and branchial hyperventilation were stimulated by chemoreceptors sensitive to both systemic and water O-2 levels. Sight of a model avian predator elicited bradycardia and hypoventilation, a fear response that inhibited reflex hyperventilation following external NaCN. The time lag to initiation of ASR following NaCN increased, but response intensity ( number of events, time at the surface) was unchanged. Mullet, however, modified their behavior to surface under shelter or near the aquarium edges. Turbid water abolished the fear response and effects of the predator on gill ventilation and timing of ASR following external NaCN, presumably because of reduced visibility. However, in turbidity, mullet consistently performed ASR under shelter or near the aquarium edges. These adaptive modulations of ASR behavior would allow mullet to retain advantages of the chemoreflex when threatened by avian predators or when unable to perceive potential threats in turbidity.