The effects of different water flow rates and feed training on the production of "pacamã" Lophiosilurus alexandri juveniles were evaluated. In the first experiment, nine day post-hatch larvae (n= 2,400) were stocked at a density of 5 larvae/L. Different water flow (F) rates were tested: F 1 = 180; F 2 = 600; F 3 = 1,300; and F 4 = 2,600mL/min. Artemia nauplii were offered as food during the first 15 days of active feeding. In the second experiment for feed training, 720 juveniles (total length of 22.2mm) were stocked at a density of 1.5 juveniles/L. A water flow rate similar to F 1 was used. The use of extruded dry diet was tested, and feed training was done with and without other enhanced flavors (Artemia nauplii or Scott emulsion). The water flow rates did not influence the survival or growth of L. alexandri. Cannibalism occurred during feed training. The worst survival, specific growth rate and high mortality were found with the use of extruded dry diet, while similar values were registered with the different feed training diets used. Reduced water flow rate can be used to lower water consumption during larviculture and feed training of L. alexandri.Keywords: feed training, juvenile production, larviculture, Lophiosilurus alexandri, water flow RESUMO Avaliaram-se os efeitos de diferentes fluxos de água e do condicionamento alimentar sobre a produção de juvenis de pacamã Lophiosilurus alexandri. Larvas com nove dias pós-eclosão (n=2.400) foram estocadas na densidade de 5 larvas/L. Diferentes fluxos (F) de água foram testados

RESUMO -Objetivou-se estudar o efeito do tamanho da presa, com ou sem adição de ração na larvicultura do pacamã (Lophiosilurus alexandri), espécie nativa da bacia do Rio São Francisco ameaçada de extinção. As larvas foram cultivadas em aquários por 16 dias e alimentadas com zooplâncton natural, selecionado em malhas de 650 e 1.300 μm, com ou sem ração.A oferta de zooplâncton de maior tamanho resultou em melhor desenvolvimento das larvas de pacamã, comprovando a vantagem do fornecimento de partículas alimentares maiores para o potencial de crescimento da espécie. O aumento na quantidade de ração não influenciou o desempenho das larvas, evidenciando a baixa ou falta de capacidade das larvas em digerir a ração ofertada. O fornecimento de ração diminuiu o pH e aumentou a condutividade elétrica, prejudicando a qualidade da água, o que não afetou o desempenho das larvas.Palavras-chave: cultivo de larvas, espécie nativa, extinção, manejo alimentar, repovoamento, sistema intensivo Effect of prey size selection and feeding on the larviculture of pacamãABSTRACT -The effect of prey size selection and feeding on pacamã Lophiosilurus alexandri larvae culture (native specie of San Francisco basin classified as threatened of extinction) was evaluated. The larvae were cultivated in aquariums during 16 days and fed with natural zooplankton, screened in 650 and 1300 μm sieve, with and without ration. The offer of zooplankton of largest size provided a better development of the pacamã larvae, demonstrating the need of alimentary particles larger for the growth potential of the species. The increase of the amount of ration did not affect the performance of the larvae, evidencing low or lack of capacity in digesting the offered ration. The ration fed reduced the pH and increased the electric conductivity, worsening water quality, which did not affect the performance of the larvae.

The influence of tank color on the visual perception of fish larvae and the success of their cultivation depends on the characteristics of each species combined with environmental factors. In this study, we determined the effect of light and dark tank colors on the larviculture of pacamã (Lophiosilurus alexandri), a species with a benthonic habit, and curimatá-pioa (Prochilodus costatus), which swims actively in the water column. Larvae of pacamã and curimatá-pioa were cultivated for 10 days in 5-L tanks, at a density of 15 larvae L -1 and luminosity of 141.7 ± 8.95 lux, and fed Artemia nauplii. Four tank colors were used: green, light blue, brown, and black (with four replications). Survival, biomass and Fulton's condition factor for pacamã larvae were similar in the different colored tanks. However, the larvae in the green tanks showed lower weight than those cultivated in black and brown tanks, as well as shorter total length than that of larvae in the brown-colored tanks. These results are probably due to the association between tank color and benthonic habitat of the pacamã. For the curimatá-pioa, survival and biomass were similar for the different colors. The weight and Fulton's condition factor were higher for the larvae cultivated in green and blue tanks. This result could be associated with the adaptation of curimatá-pioa larvae to active swimming in the water column, searching for prey.A interferência da cor do tanque na percepção visual da larva de peixe e no sucesso do seu cultivo depende da caraterística de cada espécie combinada com fatores ambientais. Neste estudo foi investigado o efeito de tanques de cores claras e escuras na larvicultura do pacamã Lophiosilurus alexandri, espécie de hábito bentônico, e, curimatá-pioa Prochilodus costatus, que nada ativamente na coluna da água. Larvas de pacamã e de curimatá-pioa foram cultivadas por 10 dias, em tanques contendo 5 L de água, a uma densidade de 15 larvas L -1 , luminosidade de 141.7 ± 8.95 lux, alimentados com náuplios de Artemia. Quatro cores de tanques foram usadas: verde e azul claras, marrom e preta (com quatro repetições). Para as larvas de pacamã, a sobrevivência, biomassa e o fator de condição de Fulton foram similares entre os tanques de diferentes cores. Entretanto, as larvas nos tanques verdes apresentara um peso menor do que as cultivadas nos tanques de cor preta e marrom, assim como um menor comprimento total, que as larvas cultivadas em tanque marrom. Estes resultados provavelmente têm origem da associação da cor do tanque com o hábito bentônico do pacamã. Para o curimatá-pioa, a sobrevivência e a biomassa foram similares entre as cores. O peso e o fator de condição de Fulton foram maiores para as larvas cultivadas nos tanques de cor verde e azul, seguidas pelo marrom e preto. Este resultado pode estar associado a adaptação das larvas de curimatá-pioa a natação ativa na coluna da água à procura de presa.

Resumo -O objetivo deste trabalho foi avaliar o efeito de diferentes cores de tanques na larvicultura de Brycon orthotaenia, durante os primeiros dez dias de criação. Foram avaliados tanques de cores claras (branco, azul claro e verde claro) e escuras (marrom e preto). Como alimento, utilizaram-se larvas de Prochilodus costatus, até o quinto dia de alimentação, e a partir do terceiro dia foi também fornecida ração comercial com 55% de proteína bruta. Foram analisados: o crescimento, a sobrevivência e o fator de condição de Fulton. Aos cinco dias, tanto o peso como o comprimento total e a taxa de crescimento específi co (TCE) foram semelhantes entre os tratamentos. No entanto, aos dez dias, animais mantidos em tanques de cores escuras apresentaram menor peso e comprimento total, porém, com TCE semelhante apesar das diferentes cores de tanque. O fator de condição de Fulton, ao fi nal do experimento, foi menor nos animais mantidos em tanques escuros. A sobrevivência foi menor em tanques de cor preta, aos cinco e dez dias de criação. Os maiores valores foram registrados nos tanques de cores marrom, verde claro e branco. Tanques claros são recomendados para a larvicultura de B. orthotaenia, pelo melhor desempenho e sobrevivência dos animais.Termos para indexação: Brycon orthotaenia, alimentação, canibalismo, manejo. Matrinxã larviculture in tanks of different colorsAbstract -The objective of this work was to evaluate the effect of different color tanks on Brycon orthotaenia larviculture, during the fi rst ten days of rearing. Light color tanks (white, light blue and light green) and dark tanks (brown and black) were evaluated. The fi shes were fed with Prochilodus costatus larvae until the 5 th day and, from the 3 rd day on, commercial dry feed with 55% crude protein was also supplied. The growth, survival and Fulton's condition factor were evaluated. At fi ve days of feed, the weight, total length and specifi c growth rate (SGR) were similar among treatments. However, after ten days, the animals kept in dark tanks showed the lowest weight and total length; but the SGR was similar despite the different color tanks. The Fulton's condition factor, observed at the end of the experiment, was lower in animals reared in dark tanks. The survival was lower in black tanks, at fi ve and ten days of rearing. The best survival, at the end of the experiment, was observed in brown, light green and white tanks. Light tanks are recommended for B. orthotaenia larviculture, for animals' best development and survival.

ABSTRACT. The aim of this study was to evaluate three stocking densities (20, 40 and 60 larvae L -1 ), and two daily prey concentrations (400 and 700 Artemia nauplii larvae -1 ) during the first seven days of active feeding (first phase). In the second phase was evaluate the effect of the different feeding regimes: fasting, dry diet (55% crude protein), Artemia sp. and mixed feeding (Artemia sp. plus dry diet), after 17 days of active feeding on Rhinelepis aspera larviculture. In the first phase, growth was affected only by prey concentration. In the second phase, the dry diet induced higher growth rates than fasting, but lower growth rates than the other treatments. The acceptance of the dry diet was evidenced by an increase in the growth rate from 4.6% day -1 in the first five days to 10.7% day -1 in the following five days of feeding. Survival was similar among dry diet, mixed feeding and Artemia nauplii treatments. R. aspera larvae can be reared during the first seven days of active feeding at a density of 60 larvae L -1 , after which they can be fed with a commercial dry diet.