ABSTRACT. Ractopamine is a drug used as an additive in animal production to improve growth, body composition, and production efficiency, although its use in fish is still poorly known. This study aimed to evaluate ractopamine hydrochloride (RAC) effects at increasing levels (0, 10, 20, and 40 mg kg−1) in Nile tilapia (Oreochromis niloticus) diets during 40 days by considering growth performance, body composition, and muscle fiber morphometry. One hundred and twelve fish (mean initial weight 518.63 ± 5.49 g) were housed in 16 circular tanks (450 L), following a completed randomized design with four treatments and four replicates. Body composition was significantly affected (P < 0.05), and the content of lipids in fish fillets dropped 26.7% (20 mg kg−1 RAC) and 26.1% (40 mg kg−1 RAC), as well as the amount of unsaturated fatty acids C14:0 and C18:0 in fish fillets (P < 0.05) by treatment with 10 mg kg−1 of RAC. Results demonstrate that fish fed 20 mg kg−1 RAC for 40 days changed Nile tilapia fillet chemical composition, decreasing lipid levels, altering the fatty acid profile, and increasing protein levels. RAC did not affect any productive performance parameters evaluated for muscle fiber morphometry.

RESUMO O presente estudo teve como objetivo avaliar a influência do óleo essencial de alho (OEA) sobre o desempenho produtivo e as variáveis morfométricas de pós-larvas de acará severo (Heros severus). Foi realizado ensaio de crescimento com 150 pós-larvas severas (1,6 ± 0,03 mg e 5,58 ± 0,1 mm), distribuídas em quinze aquários de 1 L, com aeração constante. Os peixes foram distribuídos em delineamento inteiramente casualizado com cinco tratamentos, dietas contendo diferentes níveis de OEA (0,00; 0,05; 0,50; 1,00 e 1,50 g kg-1) e três repetições. As dietas foram oferecidas quatro vezes ao dia, até saciedade aparente, por 30 dias. Ao final do experimento, os peixes foram contados, pesados e medidos, para avaliação do desempenho produtivo e das variáveis morfométricas. O aumento dos níveis de OEA na dieta resultou em redução linear nos parâmetros de desempenho produtivo, com exceção da taxa de sobrevivência e uniformidade de peso e comprimento do lote, que não apresentaram diferenças significativas, assim como as variáveis morfométricas. Concentrações elevadas de OEA na dieta podem ser prejudiciais para larvas e pós-larvas de peixes, que podem ser mais sensíveis ao dano potencial que altas concentrações deste óleo essencial podem causar. Portanto, a inclusão de OEA em níveis acima de 0,05 g kg-1 em dietas para pós-larvas de acará severo não é recomendada.

ABSTRACT The present study aimed to evaluate the influence of garlic essential oil (GEO) on the growth performance and morphometric variables of severum (Heros severus) post-larvae. A growth trial was performed using 150 severum post-larvae (1.6 ± 0.03 mg and 5.58 ± 0.1 mm), distributed in fifteen 1-L aquaria, with constant aeration. The fish were essayed in a completely randomized design with five treatments, using diets containing graded levels of GEO (0.00, 0.05, 0.50, 1.00 and 1.50 g kg-1) and three replicates. The diets were offered four times a day, until apparent satiation, for 30 days. At the end of the experiment, the fish were counted, weighed and measured, to evaluate growth performance and morphometric variables. Increased diet levels of GEO resulted in a linear reduction in growth performance parameters, except for the survival rate, weight and length uniformity of the batch, and morphometric variables which did not present significant differences. Elevated concentrations of dietary GEO may be detrimental to larvae and post-larvae of fish, which could be more sensitive to the potential damage that high concentrations of this essential oil may cause. Therefore, the inclusion of GEO in levels above 0.05 g kg-1 in diets for severum post-larvae is not recommended.

ABSTRACT The influence of feeding frequency on growth performance, batch uniformity, and survival rate of severum (Heros severus) larvae and juveniles was investigated in two experiments. In the first, 200 five-day-old severum larvae with 3.20±0.31 mg and 6.20±0.39 mm were randomly distributed into 20 aquaria (1 L) and fed 500 Artemia nauplii larvae−1 day−1 for 15 days. In the second, 120 severum juveniles, 178.19±33.59 mg and 1.82±0.09 cm, were randomly distributed into 15 aquaria (300 L) and hand-fed a commercial diet (400.0 g kg−1 crude protein and 21.2 kJ g−1 gross energy) until apparent satiety for 30 days. For both experiments, feeding frequencies of one, two, three, four, and five meals day−1 were evaluated. We used four replicates for the first experiment and three for the second. At the end of both experiments, survival rate and batch uniformity were unaffected by the feeding frequency. Severum larvae fed three, four, and five meals day−1 showed higher final weight, weight gain, and specific growth rate, but only the larvae fed five meals day−1 showed higher final length and length gain than those fed once and twice day−1. Severum juveniles fed two, four, and five meals day−1 showed higher final weight, weight gain, and specific growth rate. Growth performance parameters of final length and length gain were not affected by feeding frequencies. Thus, we recommend that the optimal feeding frequency for severum larvae fed Artemia nauplii is three meals day−1 and for juvenile severum fed a commercial diet, the optimal frequency is two meals day−1.

Resumo: O objetivo deste trabalho foi determinar o efeito do fotoperíodo sobre o canibalismo, o crescimento e a composição corporal de juvenis de trairão (Hoplias intermedius). Um delineamento inteiramente casualizado foi empregado, com quatro fotoperíodos - 0L:24D, 6L:18D, 12L:12D e 18L:6D horas de luz (L) por horas de escuridão (D) - e quatro repetições, pelo período de 90 dias. Os parâmetros analisados foram: canibalismo, crescimento em peso e comprimento, consumo alimentar, conversão alimentar, taxa de eficiência proteica, crescimento muscular e composição corporal (umidade, lipídios, cinzas e proteína bruta). Os peixes do fotoperíodo 12L:12D apresentaram maior taxa de sobrevivência e nenhum canibalismo, bem como grande uniformidade nos valores de comprimento e massa ao final do experimento. O melhor fotoperíodo para juvenis de trairão é 12L:12D, uma vez que os peixes mostraram uniformidade de crescimento e nenhum canibalismo, enquanto peixes dos grupos 6L:18D e 18L:6D apresentaram maior diâmetro de fibras musculares brancas e maior frequência de fibras de maior diâmetro. Os peixes apresentaram menor valor de lipídios no fotoperíodo 6L:18D, e o maior valor no 12L:12D. O fotoperíodo afeta a sobrevivência e o canibalismo; quanto à composição corporal, somente os lípidos são influenciados pelo fotoperíodo.

Abstract: The objective of this work was to determine the effect of photoperiod on the cannibalism, growth, and body composition of giant trahira (Hoplias intermedius) juveniles. A completely randomized design was employed, with four photoperiods - 0L:24D, 6L:18D, 12L:12D, and 18L:6D, hours of light (L): dark (D) - and four replicates, for a period of 90 days. The analyzed parameters were: cannibalism, growth in weight and length, food consumption, feed conversion, protein efficiency rate, muscle growth, and body composition (moisture, lipid, ash, and crude protein). Fish from the 12L:12D photoperiod showed the highest survival rate and no cannibalism, as well as a great uniformity for length and mass values at the end of the experiment. The best photoperiod for giant trahira juveniles is 12L:12D, as these fish showed growth uniformity and no cannibalism, while fish from the 6L:18D and 18L:6D groups had a greater diameter of white muscle fibers and a higher frequency of greater diameter fibers. Giant trahira showed the lowest value for lipids at 6L:18D and the highest value at 12L:12D. Photoperiod affects survival and cannibalism; regarding body composition, only lipids are influenced by photoperiod.

Resumo: O objetivo deste trabalho foi avaliar o desempenho, a composição corporal e o estado fisiológico de alevinos de tambaqui (Colossoma macropomum), alimentados com dietas com diferentes teores de extrato de chá-verde (Camellia sinensis, ECV). Utilizou-se um delineamento inteiramente casualizado, com cinco tratamentos, diferentes níveis de ECV (0,00, 0,05, 0,30, 0,55 e 0,80 g kg-1) e três repetições. As dietas foram oferecidas aos alevinos duas vezes ao dia, por 90 dias. O aumento dos níveis de ECV na dieta promoveu um efeito quadrático positivo sobre lipídeo corporal, lipídeo hepático, retenção de lipídeo corporal, glicose e triglicerídeos totais, e os valores mínimos destas variáveis foram estimados com níveis de 0,61, 0,54, 0,73, 0,60 e 0,30 g kg-1 ECV na dieta, respectivamente. Houve efeito quadrático negativo sobre proteína corporal e hemoglobina, com o aumento dos níveis de ECV na dieta, e os valores máximos destas variáveis foram estimados com níveis de 0,59 e 0,46 g kg-1 ECV na dieta, respectivamente. Houve redução linear dos níveis de colesterol total, com o aumento dos níveis de inclusão do ECV na dieta. A inclusão de ECV na dieta, apesar de não influenciar o desempenho, reduz a gordura corporal e a do fígado; diminui o colesterol total, os triglicerídeos e a glicose; e promove o aumento da proteína corporal de alevinos de tambaqui, o que melhora a condição de saúde deste peixe, durante o cultivo, e a qualidade do produto final.

Abstract: The objective of this work was to evaluate the performance, body composition, and physiological state of tambaqui (Colossoma macropomum) fingerlings fed diets containing different levels of green tea (Camellia sinensis) extract (GTE). A completely randomized design was used with five treatments, different levels of GTE (0.00, 0.05, 0.30, 0.55, and 0.80 g kg-1) and three replicates. The diets were offered to fingerlings twice a day, for 90 days. The increase of dietary GTE levels promoted a positive quadratic effect on body lipids, hepatic lipids, retention of body lipids, glucose, and total triglycerides, and the minimum values of these variables were estimated with 0.61, 0.54, 0.73, 0.60, and 0.30g kg-1 GTE in the diet, respectively. There was a negative quadratic effect of the extract on body protein and hemoglobin with the increased GTE dietary level, and the maximum values of these variables were estimated with 0.59 and 0.46 g kg-1 GTE dietary level, respectively. Total cholesterol levels showed a linear reduction with increased GTE dietary level. The inclusion of GTE in the diet, although not affecting performance, decreases body and hepatic fat; reduces the levels of total cholesterol, triglycerides, and glucose; and promotes the increase of body protein of tambaqui fingerlings, improving fish health conditions, during cultivation, and the quality of the final product.

ABSTRACT The objective of this work was to evaluate the influence of photoperiod on growth, uniformity, and survival of larvae of the Amazonian ornamental fish severum (Heros severus). A completely randomized study was used with five treatments (0L:24D, 6L:18D, 12L:12D, 18L:6D, 24L:0D) and four replicates, with the aquaria as the experimental unit. Two hundred severum larvae (3.20±0.16 mg and 5.60±0.00 mm) were distributed into 20 aquariums of one litre at a density of 10 larvae per litre. For a period of 15 days, feed was supplied four times daily with Artemia nauplii in a proportion of 160 nauplii/larvae/feeding. At the end of the experimental period, growth, uniformity, and survival data were subjected to analyses of variance and significance. Manipulation of the photoperiod showed no change in variables because there was no difference in the growth, uniformity, or survival of severum larvae. Thus, for larvae of this species of up to 20 days of age, the manipulation of the photoperiod is not advantageous due to the possible increase in production costs. Therefore, it is recommended to use the photoperiod close to the natural environment.

Com este estudo objetivou-se avaliar o efeito do fotoperíodo sobre a composição centesimal de filés de juvenis de tilápia do Nilo. Utilizou-se um delineamento inteiramente casualizado com cinco tratamentos (0L:24E; 6L:18E; 12L:12E; 18L:6E; 24L:0E) e quatro repetições. Foram utilizados 160 alevinos de tilápia, distribuídos em 20 aquários (20L) em sistema de recirculação, temperatura controlada em 27 ºC e densidade de oito peixes por aquário. Os peixes foram alimentados duas vezes ao dia, com ração comercial extrusada contendo 40% de proteína bruta. Ao final de 75 dias, amostras do filé foram coletadas e armazenadas em freezer (-80 ºC) para posteriores análises da composição bromatológica. Não houve efeito dos diferentes fotoperíodos sobre a umidade e cinzas do filé (P>0,05). Por outro lado, os peixes sob fotoperíodo de 18L:6E apresentaram maior quantidade de proteína e retenção desta no filé, assim como menor quantidade de gordura e retenção de lipídeo (P<0,05). Portanto, pode-se concluir que o fotoperíodo pode alterar a composição corporal de alevinos de tilápia do Nilo, sendo que e o fotoperíodo de 18L:6E contribui para o aumento da concentração de proteína bruta e uma menor deposição de gordura no filé.

This study aimed to evaluate the effect of the photoperiod on the fillet composition of Nile tilapia juveniles. We employed a completely randomized design with five treatments (0L:24D, 6L:18D, 12L:12D, 18L:6D, 24L:0D) and four replications. We used 160 Nile tilapia juveniles, distributed in 20 tanks containing 20 liters of water, in a recirculation systems, at controlled temperature of 27 ºC and density of eight fish per tank. Fish were fed twice a day with commercial extruded feed containing 40% crude protein. Samples of the fillet at the end of 75 days were collected and stored in a freezer at -80 ºC for subsequent analysis of chemical composition. There was no effect of photoperiod on moisture and ash content of the fillet (P>0.05). The period 18L:6D showed higher amounts of protein in the fillet, as well as lower amounts of fat (P<0.05). Therefore, it can be concluded that the photoperiod can alter Nile tilapia body composition, and the photoperiod 18L:6D contributed to the higher concentration of crude protein and lower fat deposition in Nile tilapia fillets.

The objective of this study was to evaluate the effect of photoperiod on locomotor activity, growth and gonadal development in Nile tilapia (Oreochromis niloticus) fingerlings. A completely randomised design was used, with five treatments (0L:24D, 6L:18D, 12L:12D, 18L:6D and 24L:0D) and four replicates, with the aquarium as the experimental unit. One hundred and sixty fingerlings of tilapia weighing 3.21±0.05 g and measuring 4.35±0.07 cm each were distributed among 20 aquaria of 20 L in a recirculation system with the temperature controlled to 27 °C, with eight fish per aquarium. Feeding was carried out twice daily for 75 days, with extruded feed containing 40% crude protein. The fingerlings subjected to a photoperiod of 12L:12D as well as those under 18L:6D and 24L:0D showed the greatest locomotor activity, whereas those under 6L:18D and 0L:24D showed the lowest activity. Fish subjected to a photoperiod of 18L:6D and 24L:0D showed the highest levels of performance. However, manipulation of the photoperiod did not influence the gonadal development, survival or the appearance of deformities in juvenile Nile tilapia. Under long photoperiods (18L:6D and 24L:0D), fish direct their energy to somatic growth and induce best feed efficiency.

O objetivo deste trabalho foi determinar os níveis apropriados de proteína e energia em dietas para alevinos de trairão (Hoplias lacerdae). Os níveis de proteína bruta (PB) e energia bruta (EB) foram avaliados em delineamento inteiramente casualizado em esquema fatorial 4x3, com 35, 39, 43 e 47% PB e 4.100, 4.300 e 4.500 kcal kg-1 de EB, e quatro repetições. A taxa de sobrevivência foi de 99,22%, e um aumento linear nos índices de desempenho foi detectado após aumento dos níveis de proteína bruta na dieta. A conversão alimentar decresceu com o aumento dos níveis de proteína e energia na dieta. Foi observada interação significativa entre a proteína e energia bruta sobre a proteína corporal e matéria mineral. O lipídeo corporal aumentou linearmente com o aumento da energia bruta das dietas. A retenção de proteína e energia bruta mostrou aumento linear com os níveis crescentes de proteína bruta nas dietas. Dietas com 47% proteína bruta proporcionam o melhor desempenho e a melhor retenção de energia, independentemente de seus níveis de energia bruta.

The objective of this work was to determine the proper levels of protein and energy in diets of Hoplias lacerdae fingerlings. The dietary crude protein (CP) and gross energy (GE) levels for fingerlings of giant trahira were evaluated in a completely randomized 4x3 factorial design with 35, 39, 43 and 47% CP and 4,100, 4,300 and 4,500 kcal kg-1 of GE, and four replicates. The survival rate was 99.22%, and a linear improvement on the performance parameters was detected after increasing diet crude protein levels. Feed conversion ratio decreased with increasing levels of dietary protein and energy in the diets. A significant interaction between crude protein and gross energy was observed over body protein and mineral matter. Body lipid has increased linearly as gross energy in the diet increased. The retention of crude protein and energy showed a linear increasing with rising of crude protein levels in the diet. Crude protein level at 47% provides the best performance and energy retention, independently of the gross energy levels in the diet.

Com o objetivo de avaliar a tolerância de Betta splendens à salinidade da água, realizou-se um experimento em delineamento inteiramente casualizado, com seis concentrações de sal na água (0; 3; 6; 9; 12 e 15 g de sal comum/L de água), cada uma com cinco repetições (1 peixe/repetição). Fêmeas adultas de Betta splendens foram alojadas individualmente em aquários mantidos em estufa incubadora, a 26 ± 0,2 ºC e fotoperíodo de 12 horas. Os peixes foram alimentados até a saciedade, uma vez ao dia, com ração comercial. Foram mensurados o consumo diário de ração e a sobrevivência dos peixes a cada 12 horas. Para avaliar o efeito agudo da salinidade, foram calculados o tempo médio de sobrevivência e a salinidade letal mediana-96 horas, enquanto o efeito crônico (18 dias) foi avaliado pelo cálculo da salinidade máxima de sobrevivência e da salinidade letal mediana. O tempo médio de sobrevivência foi significativamente menor na salinidade de 15 g/L. A salinidade letal mediana-96 horas estimada foi de 11,88 g/L, a salinidade máxima de sobrevivência entre 6 e 7 g/L, e a salinidade letal mediana de 9,35 g/L. Observou-se interação significativa entre as salinidades da água e o tempo de alimentação. Considerando que é uma espécie de água doce, o beta possui alta tolerância à salinidade da água.

Salinity tolerance of Betta splendens was evaluated in a complete randomized design, with six salt concentrations in the water (0; 3; 6; 9; 12 and 15 g common salt/L) with five replications (1 fish/replication). Adult female B. splendens were individually placed in aquariums in an incubation chamber at 26 ± 0.2ºC and 12-hour photoperiod. Fish were fed to satiation, once a day, with commercial diet. Feed intake and survival rate were measured every 12 hours. To evaluate the effect of acute salinity, the mean survival time and median lethal salinity-96 h were calculated, while the chronic effect (18 days) was assessed by calculating the survival salinity maximum and median lethal salinity. The mean survival time was significantly lower at 15 g/L water salinity. The median lethal salinity-96 h calculated was 11.88 g/L, the survival salinity maximum was between 6 and 7 g/L, and the median lethal salinity was 9.35 g/L. There was a significant interaction between feeding time and water salinity. Considering that the B. splendens is a freshwater species, it was concluded that this species demonstrated a high tolerance to water salinity.