Daily variation feeding of Astyanax lacustris (Lütken 1875) in a subtropical river

This study aimed to know the daily variation of Astyanax lacustris (Lütken 1875) feeding in a lotic environment. Fish were caught with a net for three days every three hours in the summer to capture ten individuals per hour in a stretch of the Ijuí River, Middle Uruguay River, Brazil. The captured specimens had their stomachs removed and the content analyzed and separated into seven food categories with the aid of stereomicroscope. For the analysis of food items were used the frequency of occurrence methods, volumetric method and applied the Alimentary Index (IAi). Two hundred stomachs were analyzed, of which 95% had food content. The most abundant items were algae and autochthonous insects. Astyanax lacustris feeds throughout the day especially early in the morning (9 hours) and reduces its feeding at night (24 hours and 3 hours). It was also verified variation of AI of different food items throughout the day. It is concluded that A. lacustris feeds throughout the day, especially in the daytime and that throughout the 24 hours it varies its diet due to photoperiod and food availability.

Probiotic supplementation causes hematological changes and improves non-specific immunity in Brycon amazonicus

A commercialprobioticcontaining Bacillussubtilis(109 CFU g-1) was evaluated incaged matrinxã,Bryconamazonicus,by measuring hematological parametersand macrophage activity after 42 and 84 days after feeding. The product wasadded tocommercial feed using 2%soybean oil as a protectant. A randomized three-treatmentexperiment was performed using fourreplicates per treatment. The groups included: (a) control without probiotic, (b) 5 g kg-1probiotic, and (c) 10 g kg-1probiotic. Forhematological analysis,eightfishper treatmentwere used to determinetotal cell count (RBC); thrombocytes, differential, and total leukocyte count (TLC); hematocrit (Htc); hemoglobin tax; mean corpuscular volume (MCV); and mean corpuscular hemoglobin concentration (MCHC). Furthermore, plasma cortisol and glucose levels were measured in blood samples. Macrophage phagocytic activity was evaluated by injecting Saccharomyces cerevisiae(11,000 cells in a 3 mLvolume) into the coelomic cavity incubating for 8hours.Addition of probiotics to the diet of caged matrinxã altered the Htc, RBC, MCV, MCHC, TLC, lymphocyte, and eosinophil values. We observed increased cortisol and glucose levels and phagocytic activity, but no increase in the phagocytic index. We thus conclude that supplementing caged Brycon amazonicuswith probiotics improves their non-specific immunity and alters blood profiles.

Water temperature, body mass and fasting heat production of pacu (Piaractus mesopotamicus)

ABSTRACT Knowledge on fasting heat production (HEf) of fish is key to develop bioenergetics models thus improving feeding management of farmed species. The core of knowledge on HEf of farmed, neotropical fish is scarce. This study assessed the effect of body mass and water temperature on standard metabolism and fasting heat production of pacu, Piaractus mesopotamicus, an omnivore, Neotropical fresh water characin important for farming and fisheries industries all through South American continent. An automated, intermittent flow respirometry system was used to measure standard metabolic rate (SMR) of pacu (17 - 1,050 g) at five water temperatures: 19, 23, 26, 29 and 33 °C. Mass specific SMR increased with increasing water temperature but decreased as function of body mass. The allometric exponent for scaling HEf was 0.788, and lied in the range recorded for all studied warm-water fish. The recorded van't Hoff factor (Q10) for pacu (2.06) shows the species low response to temperature increases. The model HEf = 0.04643×W0.7882×T1.837 allows to predict HEf (kJ d-1) from body mass (W, kg) and water temperature (T, °C), and can be used in bioenergetical models for the species.

Water quality assessment of the Sinos River – RS, Brazil / Qualidade da água do Rio dos Sinos – RS, Brasil

Worldwide environmental pollution is increasing at the same rate as social and economic development. This growth, however, is disorganized and leads to increased degradation of water resources. Water, which was once considered inexhaustible, has become the focus of environmental concerns because it is essential for life and for many production processes. This article describes monitoring of the water quality at three points along the Sinos River (RS, Brazil), one in each of the upper, middle and lower stretches. The points were sampled in 2013 and again in 2014. The water samples were analyzed to determine the following physical and chemical parameters plus genotoxicity to fish: metals (Cr, Fe, Al), chemical oxygen demand, biochemical oxygen demand, chlorides, conductivity, total suspended solids, total phosphorous, total and fecal coliforms, pH, dissolved oxygen, turbidity, total Kjeldahl nitrogen nitrate and ammoniacal nitrogen. Genotoxicity was tested by exposing individuals of the species Astyanax jacuhiensis to water samples and then comparing them with a control group exposed to water from the public water supply. The results confirmed the presence of substances with genotoxic potential at the sample points located in the middle and lower stretches of the river. The results for samples from the upper stretch, at P1, did not exhibit differences in relation to the control group. The physical and chemical analyses did not detect reductions in water quality in the lower stretch, as had been expected in view of the large volumes of domestic and industrial effluents discharged into this part of the river.

Resumo A poluição ambiental aumenta mundialmente, no mesmo ritmo que o desenvolvimento social e econômico. Este crescimento é, muitas vezes, desorganizado e proporciona um aumento da degradação dos recursos hídricos. Água, que já foi considerado inesgotável, tornou-se o foco das preocupações ambientais, pois é essencial para a vida e para muitos processos de produção. Este artigo aborda o monitoramento da qualidade da água, em três pontos do Rio dos Sinos, compreendendo o trecho superior, médio e inferior. Os pontos foram monitorados entre 2013 e 2014. As amostras de água foram analisadas para determinar os parâmetros físico-químicos complementarmente a genotoxicidade em peixes: metais (Cr, Fe, Al), demanda química de oxigenio, demanda bioquímica de oxigênio, cloretos, condutividade, sólidos suspensos totais, fósforo total, coliformes totais e fecais, pH, oxigênio dissolvido, turbidez, nitrogênio total Kjeldahl, nitrato e nitrogênio amoniacal. A avaliação de genotoxicidade foi conduzida pela exposição à água de diferentes pontos do rio de indivíduos da espécie Astyanax jacuhiensis. O grupo controle foi exposto à água de abastecimento público. Os resultados confirmam a presença de substâncias com potencial genotóxico nos pontos localizados nos trechos médio e inferior. No trecho superior, ponto 1, não houve diferenças em relação ao grupo controle. A diminuição da qualidade da água do trecho inferior quando comparada com o superior também foi confirmada através das análises físico-químicas, as quais indicaram uma redução na qualidade da água nos trechos inferiores, como o esperado devido ao grande escoamento de esgotos domésticos e industriais neste trecho do rio.

Evaluation of genotoxicity and cytotoxicity of water samples from the Sinos River Basin, southern Brazil / Avaliação da genotoxicidade e da citotoxicidade de amostras de água da Bacia do Rio dos Sinos, sul do Brasil

Some water bodies in the Sinos River Basin (SRB) have been suffering the effects of pollution by residential, industrial and agroindustrial wastewater. The presence of cytotoxic and genotoxic compounds could compromise the water quality and the balance of these ecosystems. In this context, the research aimed to evaluate the genotoxicity and cytotoxicity of the water at four sites along the SRB (in the cities of Santo Antônio da Patrulha, Parobé, Campo Bom and Esteio), using bioassays in fish and cell culture. Samples of surface water were collected and evaluated in vitro using the Astyanax jacuhiensis fish species (micronucleus test and comet assay) and the Vero lineage of cells (comet assay and cytotoxicity tests, neutral red - NR and tetrazolium MTT). The micronucleus test in fish showed no significant differences between the sampling sites, and neither did the comet assay and the MTT and NR tests in Vero cells. The comet assay showed an increase in genetic damage in the fish exposed to water samples collected in the middle and lower sections of the basin (Parobé, Campo Bom and Esteio) when compared to the upper section of the basin (Santo Antônio da Patrulha). The results indicate contamination by genotoxic substances starting in the middle section of the SRB.

Alguns corpos d’água da Bacia Hidrográfica do Rio dos Sinos (BHRS) vêm sofrendo os efeitos da poluição por efluentes domésticos, industriais e agroindustriais. A presença de compostos citotóxicos e genotóxicos pode comprometer a qualidade da água e o equilíbrio desses ecossistemas. Neste contexto, o objetivo do trabalho foi avaliar a genotoxicidade e a citotoxicidade da água em quatro pontos ao longo da BHRS (Santo Antônio da Patrulha, Parobé, Campo Bom e Esteio), utilizando bioensaios em peixes e em cultura celular. As amostras de água de superfície foram coletadas e avaliadas in vitro utilizando a espécie de peixe Astyanax jacuhiensis (teste de micronúcleo e ensaio cometa) e a linhagem celular tipo Vero (ensaio cometa e os testes de citotoxicidade vermelho neutro - VN e tetrazólio MTT). O teste de micronúcleos em peixes não apresentou diferenças significativas entre os pontos de coleta, assim como o ensaio cometa e os testes VN e MTT nas células Vero. O ensaio cometa demonstrou aumento nos danos genéticos em peixes expostos às amostras de água coletadas nos trechos médio e inferior da bacia (Parobé, Campo Bom e Esteio) em relação ao trecho superior da bacia (Santo Antônio da Patrulha). Os resultados indicam contaminação por substâncias genotóxicas a partir do trecho médio da BHRS.

Fósforo na alimentação de pacus criados em tanques-rede / Phosphorus in the feeding of pacus reared in net-cages

Avaliaram-se o desempenho zootécnico, as características da carcaça, as características hematológicas e bioquímicas, a composição química e também a qualidade da água na criação de pacus Piaractus mesopotamicus em tanques-rede em reservatório e alimentados com dietas que continham diferentes quantidades de fósforo total. Foram utilizados 3.000 peixes, distribuídos em um delineamento inteiramente ao acaso, com cinco tratamentos e quatro repetições em 20 tanques-rede, sendo a unidade experimental composta por um tanque com 150 peixes. Os tratamentos foram constituídos por cinco dietas, elaboradas de modo a conterem quantidades de fósforo total de 6,0; 7,5; 9,0; 10,5 e 12,0g/kg por meio da suplementação de fosfato bicálcico. A quantidade de 6,0 a 12,0g/kg de fósforo total na ração pode ser utilizada na alimentação de pacus criados em tanques-rede, sem que haja comprometimento do desempenho dos animais, e pode-se recomendar, comercialmente, 6,0g/kg de fósforo total em dietas para pacus...

The aim of this study was to evaluate the zootechnical performance, carcass characteristics, hematologic and biochemical characteristics, chemical composition and water quality in the rearing of pacus Piaractus mesopotamicus in cages in the reservoir fed with diets containing different total phosphorus quantities. A total of 3,000 fish allotted to a completely randomized design were used with five treatments and four replications in 20 cages, and the experimental unit consisted of a tank with 150 fish. The treatments were formed by five diets made to contain total phosphurus quantities of 6.0; 7.5; 9.0; 10.5 and 12.0g/kg through supplementation of dicalcium phosphate. The quantities of 6.0 to 12.0g/kg of total phosphurus can be used in the feeding of pacus reared in cages without compromising the animals' performance and the use of 6.0 g/kg total phosphorus in diets for pacus can be commercially recommended...

Farinha de folha de leucena (Leucaena leucocephala Lam. de wit) como fonte de proteína para juvenis de tambaqui (Colossoma macropomum CUVIER, 1818) / Leucaena leaf flour (Leucaena leucocephala Lam. of wit) as a protein source for juveniles of tambaqui (Colossoma macropomum Cuvier, 1818)

The tambaqui (Colossoma macropomum) is an omnivorous fish native to the Amazon basin, which has high commercial value. Characteristics of rusticity and desirable growth in farming highlight this species for breeding in captivity. However, in commercial fish breeding, feed costs may represent 60-80% of total costs of production, being the protein the most expensive nutrient in the diet. The objective of this study was to evaluate the growth of juvenile tambaqui fed with diets containing leucaena leaf flour as protein source. A total of 240 juveniles were distributed in 12 experimental aquaria (350 L) in a completely randomized design with four treatments (0%, 8%, 16%, 24% of inclusion of leucaena leaf flour in diet) and three replications. Weight gain, feed conversion ratio, specific growth rate, protein efficiency rate and cost of production per kilogram of live weight gained were calculated. For the studied variables, there was no significant difference (p> 0.05) among treatments, indicating that it is possible to include up to 24% of leucaena leaf flour in diets for juveniles of tambaqui, without compromising the variables studied, although the replacement has not represented reduction in cost of production per kilogram of fish.

O tambaqui (Colossoma macropomum) é um peixe onívoro, natural da bacia amazônica, que possui elevado valor comercial. Características de rusticidade e desempenho produtivo destacam esta espécie para criação em cativeiro. Contudo, em criações comerciais de peixes, os custos com alimentação podem corresponder de 60 a 80% dos custos totais de produção, sendo a proteína o nutriente mais caro da dieta. O objetivo deste trabalho foi avaliar o desempenho produtivo de juvenis de tambaqui alimentados com rações contendo farinha de folha de leucena como fonte protéica. 240 juvenis foram distribuídos em 12 aquários experimentais (350 L), em um delineamento experimental inteiramente casualizado com quatro tratamentos (0%, 8%, 16%, 24% de inclusão de farinha de folha de leucena na ração) e três repetições. Foram determinados o ganho de peso, conversão alimentar aparente, taxa de crescimento específico, taxa de eficiência protéica e custo de produção do quilograma de peso vivo ganho. Para as variáveis estudadas, não houve diferença significativa (p>0,05) entre os tratamentos, indicando que é possível incluir até 24% de farinha de folha de leucena em rações para juvenis de tambaqui, sem comprometimento das variáveis estudadas, embora a substituição não tenha representado redução no custo de produção do quilograma de peixe.

Mutilating predation in the Cheirodontinae Odontostilbe pequira (Characiformes: Characidae)

We observed individuals of Odontostilbe pequira, a small characid, approaching and biting individuals of larger-bodied fishes of other species. This observation was made in two clear water headwater streams of the Cuiabá basin, Paraguay River system, located in Nobres, Mato Grosso State, Brazil, which led us to investigate the behavioral interactions of these fish. We characterized behavioral interactions between species by direct underwater observations using snorkelling and video recordings. Additionally, we proceeded diet analyses of O. pequira, obtaining intestinal coefficient and the index of alimentary importance. During underwater observations we checked the relative frequency of attacks by O. pequira on larger fish species. Odontostilbe pequira attacked individually or in large groups, and the anostomid Leporinus friderici was the preferred target prey species, while Prochilodus lineatus was apparently avoided. Our study sustains that O. pequira is omnivorous, with a diet that varies seasonally. It feeds mainly on plants, but also on animal prey, including the scales of small fishes, and, possibly, the mucus and epidermis of larger fish species. We suggest the term "mutilating predation" to describe the latter relationship.

Observamos indivíduos de Odontostilbe pequira, um caracídeo pequeno, abordando e mordendo peixes maiores de outras espécies. Essa observação foi feita em dois riachos de cabeceira com águas cristalinas na bacia do rio Cuiabá, sistema do rio Paraguai, localizados em Nobres, Mato Grosso, Brasil, o que nos levou a investigar a interação comportamental desses peixes. Nós o fizemos através de observações subaquáticas diretas usando mergulho livre e vídeo. Adicionalmente, realizamos a análise da dieta de O. pequira, obtendo seu coeficiente intestinal e índice de importância alimentar. Nas observações subaquáticas avaliamos a frequência relativa dos ataques de O. pequira sobre peixes maiores. Odontostilbe pequira ataca individualmente ou em grupos grandes, o anostomídeo Leporinus friderici foi a presa preferida, enquanto Prochilodus lineatus foi evitado. Este estudo sustenta que O. pequira é um peixe onívoro cuja dieta varia sazonalmente. Ele come principalmente plantas, mas também presas animais, como escamas de peixes pequenos e, possivelmente, muco e epiderme de peixes maiores. Sugerimos o termo "predação mutilante" para descrever essa relação.