ABSTRACT This study aimed to determine the length-weight relationship and mathematical models to predict dressed and fillet weight and yield and fillet composition of wild traíra, Hoplias malabaricus (Bloch, 1794). A total of 80 marketable-sized fish from 292.28 to 2879.57 g and 32.06 to 61.19 cm were used. The length:weight ratio was estimated using the equation: W = a × L b, in which W is body weight (g) and L is length (cm). The models of dressed and fillet weight and yield and body were elaborated using first-order ( y ^ i = β 0 + β 1 x i ) or second-order ( y ^ i = β 0 + β 1 x i + β 1 x i 2 ) linear regression analyses. The value of slope b in the length:weight ratio was 3.3732 and intercept was 0.0029. The prediction equations obtained for dressed weight, fillet weight, dressed yield, fillet yield, fillet gross energy, moisture, crude protein, crude lipid, and ash were, respectively: y ^ = 0.3244 + 0.9373 W, y ^ = 0.7651 + 0.4181 W, y ^ = 939.8015 + 0.0019 W, y ^ = 420.55170 + 0.0064 W, y ^ = 997.9600 + 0.0630 W, y ^ = 810.6500 − 0.0085 W, y ^ = 184.080 − 0.0111 W, y ^ = 3.1131 + 0.0049 W, and y ^ = 10.6110 + 0.0009 W, in which W is the body weight of fish (g). We demonstrated the possibility of elaborating realistic expressions to describe degutted weight, fillet weight, and fillet composition. However, lower mathematical adjustment was observed to estimate realistic prediction of dressed and fillet yield.

ABSTRACT We aimed to evaluate the effects of Curcuma longa as growth promoter, skin pigmentation enhancer, and stress reducer in diets of Trichogaster labiosa after transport. We used five diets containing 0.0, 1.0, 5.0, 10.0, and 25.0 g kg−1 of turmeric rhizome powder. We observed quadratic effects of turmeric supplementation for feed intake, weight gain, final length, and specific growth rate. The estimated amount of turmeric that decreased these variables ranged from 15.53 to 16.39 g kg−1. Quadratic effects of supplementation of turmeric for cyan and black dorsal skin coloring indices were observed, with estimated values that increased these variables equal to 15.03 and 17.44 g kg−1, respectively. After fish transport, quadratic effects of turmeric were observed for the cyan and black dorsal skin depigmentation indices, with estimated values that increased these variables equal to 13.29 and 17.04 g kg−1, respectively. These results demonstrate that supplementation with turmeric at levels up to 17 g kg−1 causes further reduction in skin color due to the stress of transport. Thus, Curcuma longa acts neither as a growth promoter nor as a stress reducer for Trichogaster labiosa. Curcuma longa does not improve the orange pattern of skin pigmentation in the strain of T. labiosa orange thick-lipped gourami.

ABSTRACT A 90-day feeding trial was conducted to estimate the dietary lysine requirement of adult lambari ( Astyanax altiparanae ), based on growth performance, whole-body composition, muscle development, and aspartate aminotransferase (AST) and alanine aminotransferase (ALT) activities. Six isoproteic (345.0 g kg−1) and isoenergetic (19.51 MJ kg−1) diets were formulated, and crystalline L-lysine was added to obtain diets with lysine concentrations of 12.13, 13.31, 15.36, 18.79, 19.92, and 23.02 g kg−1 dry diet. Female adult lambari (n = 480; weight of 4.96±0.02 g) were distributed into 24 (70 L) aquaria and fed the experimental diets six times daily. Fish fed 12.13 to 19.92 g kg−1 lysine showed increased weight gain and percent weight gain, and fish from those treatments also showed improvement in final carcass quality by a decrease in whole-body lipid content. Fish fed 12.13 g kg−1 lysine showed lower ALT and AST activities in blood serum when compared with fish fed the highest lysine levels. No differences were observed in muscle growth in fish fed graded lysine levels. According to the broken-line model analysis of weight gain and dietary lysine levels, the dietary lysine requirement of adult lambari is estimated at 18.72 g kg−1 (5.41% of dietary protein).

RESUMO O objetivo do presente estudo foi avaliar o efeito do óleo de orégano sobre a morfometria intestinal e hepática do lambari-do-rabo-amarelo, Astyanax altiparanae. Os peixes (1,46 ± 0,09 g) foram distribuídos em aquários contendo 60 L, na densidade de 0.5 peixes L-1. Foram avaliadas seis dietas práticas contendo quantidades variadas de óleo de orégano (0,0; 0,5; 1,0; 1,5; 2,0 e 2,5 g de óleo de orégano kg-1). Ao fi nal de 90 dias, os peixes foram eutanasiados. Foi realizada a coleta de 4 intestinos e 4 fígados por tratamento, que foram fi xados em Bouin e incluídos em resina. Foi observado efeito linear crescente do óleo de orégano sobre a altura das vilosidades, largura das vilosidades, área de superfície de absorção e espessura da camada muscular. Também foi observado efeito linear decrescente sobre o número total de células caliciformes. Houve efeito linear crescente da porcentagem citoplasmática e glicogênio hepático. Para a porcentagem de núcleos dos hepatócitos e capilares houve efeito linear decrescente. Dessa forma, o óleo essencial de orégano promove o aumento da área de absorção e modula a quantidade de células caliciformes envolvidas na proteção da mucosa intestinal e promove o aumento citoplasmático, com maior deposição de glicogênio hepático no lambari-do-rabo-amarelo.

ABSTRACT This study aimed to evaluate the effect of oregano oil on the intestinal and liver morphometry of yellow tail tetra, Astyanax altiparanae. Fish (1.46 ± 0.09 g) were kept in a 60-L aquaria, at a stocking density of 0.5 fi sh L-1. Six diets containing varying amounts of oregano oil were evaluated (0.0; 0.5; 1.0; 1.5; 2.0 and 2.5 g of oregano oil kg-1). At the end of 90 days, the fi sh were euthanised. Four intestines and four livers were collected per treatment, which were fi xed in Bouin and embedded in resin. For height and width folds, the absorption surface area and thickness of the muscular layer a positive linear effect of oregano oil was observed. A decrescent linear effect on the total number of goblet cells was also observed. For the cytoplasmic percentage of hepatocytes and liver glycogen, a positive linear effect of oregano oil was observed. There was a decreasing linear effect on the percentage of nuclei in the hepatocytes and capillaries. Thus, the oregano essential oil promotes increased absorption areas, modulates the amount of goblet cells involved in protecting the intestinal mucosa and promotes cytoplasmic increase with greater deposition of liver glycogen in yellow tail tetra.

RESUMO O objetivo deste estudo foi avaliar o uso de gelatina comercial em substituição total do coração bovino no condicionamento alimentar de pacamãLophiosilurus alexandri em diferentes salinidades da água. O experimento foi realizado em delineamento inteiramente casualizado, em esquema fatorial 2 × 3, usando dois tipos de ingredientes úmidos (coração bovino e gelatina) e três salinidades da água (0,0; 2,0 e 4,0 g de sal L-¹) com três repetições cada. Juvenis (2,39 ± 0,08 cm de comprimento padrão e 0,20 ± 0,03 g de peso) foram condicionados a aceitar dietas comerciais através da técnica da transição gradual de ingredientes. Após 36 dias de experimento não foram observadas diferenças significativas para o ganho de peso, ganho em comprimento e taxa de crescimento específico. A eficiência do condicionamento alimentar foi melhor (P <0,05) com o uso da gelatina (100%). Houve efeito negativo da salinidade da água na sobrevivência e eficiência do manejo na concentração de 4 g de sal L-¹, com valores de 58,6 ± 12,0% e 58,0 ± 12,0%, respectivamente. Juvenis de Lophiosilurus alexandri podem ser condicionados a aceitar dietas comerciais com o emprego da gelatina em substituição total do coração bovino, em água doce ou na salinidade de 2 g de sal L-¹.

ABSTRACT The aim of this study was to evaluate commercial gelatin in the total replacement of bovine heart in feed training of "pacamã" Lophiosilurus alexandri in different water salinities. A completely randomized experimental design, in a 2 × 3 factorial arrangement, was performed using two types of moist ingredients (bovine heart and gelatin) and three water salinities (0.0; 2.0 and 4.0 g of salt L-1) with three replications. Juveniles (2.39 ± 0.08 cm standard length and 0.20 ± 0.03 g of weight) were conditioned to accept commercial diets by the technique of the gradual transition of ingredients. At the end of 36 days no differences were observed to weight gain, length gain and specific growth rate. The feed training efficiency was better (P < 0.05) with the gelatin use, 100.0%. There was a negative effect of salinity on the survival rate and management efficiency in the concentration of 4 g of salt L-1, with values of 58.6 ± 12.0 % and 58.0 ± 12.0 %, respectively. Lophiosilurus alexandri juveniles could be feed-trained to accept commercial diets with gelatin in the total replacement of bovine heart in freshwater or salinity of 2 g of salt L-1.

Colliroja, Astyanax fasciatus, is a new aquaculture species, and information on its dietary essential amino acid requirements is lacking. The whole body composition of 120 farmed fish (16.2 ± 8.8 g) was determined to estimate the dietary essential amino acid requirement based on the ideal protein concept ((each essential amino acid/lysine) x100), and the findings were correlated to the whole body essential amino acid content of Nile tilapia Oreochromis niloticus. The dietary essential amino acids, including cysteine and tyrosine, accounted for 5.46, 4.62, 1.16, 3.28, 5.63, 2.01, 2.59, 2.84, 4.66, 3.39, 0.65, and 3.51% of the total protein for lysine, arginine, histidine, isoleucine, leucine, methionine, methionine+tyrosine, phenylalanine, phenylalanine+tyrosine, threonine, tryptophan, and valine, respectively. There were positive linear and high correlations (r = 0.971) between the whole body amino acid profiles of colliroja and Nile tilapia. Thus, the whole body amino acid profile of colliroja might be used to estimate accurately the essential amino acid requirement.

Colirroja, Astyanax fasciatus, es una nueva especie de la acuicultura y no hay información sobre sus requerimentos de aminoácidos esenciales en la dieta. Se determinó la composición corporal de 120 peces de cultivo (16,2 ± 8,8 g) para estimar los requirimientos nutricionales de aminoácidos essenciales en la dieta, incluyendo cistina y tirosina, basada en el concepto de proteína ideal ((cada aminoácido essencial/lisina) x 100) y los resultados se correlacionaron con el perfil corporal de la tilapia del Nilo Oreochromis niloticus. El perfil dietético de aminoácidos essenciales explica el 5,46, 4,62, 1,16, 3,28, 5,63, 2,01, 2,59, 2,.84, 4,66, 3,39, 0.65 y 3,51% de la proteína, respectivamente para lisina, arginina, histidina, isoleucina, leucina, metionina, metionina+cistina, fenilalanina, fenilalanina+tirosina, treonina, triptófano y valina. Hubo una alta correlación lineal positiva (r = 0,971) entre el perfil corporal de aminoácidos de colirroja y el de tilapia del Nilo. Por lo tanto, el perfil corporal de los aminoácidos basado en el concepto de proteína ideal podría ser utilizado para estimar con precisión el requisito de aminoácidos essenciales de colirroja.

O trabalho foi realizado com o objetivo de avaliar a composição proximal e perfil de ácidos graxos de lambaris-do-rabo-vermelho de acordo com a classe de peso corporal: Classe I (3,24 - 4,46g); Classe II (9,08 - 11,62g); Classe III (15,8 - 18,89g) e Classe IV (32,25 - 54,64g). Não foi observado efeito do peso corporal sobre o conteúdo de cinzas corporal dos peixes. Os peixes de Classe I apresentaram maiores teores de umidade e menores teores de lipídios corporal em relação aos peixes das classes II, III e IV. O maior nível de lipídios foi observado em peixes da Classe IV e não sendo observadas diferenças entre peixes das Classes II, III e IV. O ácido palmitico (16:0) e oléico (18:1 n-9) foram os ácidos graxos saturados e monoinsaturados mais abundantes, respectivamente, independentemente da classe de peso dos peixes. A quantidade total de ácidos graxos saturados foi maior nos peixes da Classe I, que também apresentaram níveis mais elevados dos ácidos palmítico, linoléico e docohexaenóico. Os peixes de Classe II, III e IV apresentaram maior relação de ácidos graxos n-3/n-6 em comparação com os peixes da Classe I, porém os peixes de todas as classes de peso demonstraram valor nutricional satisfatório para consumo humano em termos de proteína bruta, lipídios e relações de ácidos graxos n-3/n-6 e AGP/AGS.

This work was carried out to evaluate the proximate composition and fatty acids acid profile of "lambari-do-rabo-vermelho" according to body weight class: I (3.24 - 4.46g); Class II (9.08 - 11.62g); Class III (15.8 - 18.89g) and Class IV (32.25 - 54.64g) with 25 fish each class of to determine the proximate and fatty acids compositions. No significant effects on the fish ash content into fish weight class were observed. Fish from Class I showed highest humidity and lowest whole body lipid levels compared to fish from classes II, III and IV. The highest level of lipid was observed in fish from Class IV and no differences were observed between fish from Classes II, III and IV. Palmitic (16:0) and oleic (18:1 n9) acids were the major saturated and monounsaturated fatty acids, respectively, in the whole body, independently of fish weight class. The total amount of saturated fatty acids was higher (P <0.05) in the fish of Class I, which also showed higher levels of palmitic, linoleic and docohexaenoic acids. Fish from Class II, III and IV showed the highest level of n-3/n-6 ratio compared to fish from Class I, but all class of fish weigh analyzed were shown nutritional value satisfactory for human consumption in terms crude protein, lipids and n-3/n-6 and AGP/AGS ratios.

O objetivo deste trabalho foi avaliar o efeito da suplementação da dieta com vitamina C no desempenho produtivo, nas alterações morfológicas e no perfil de ácidos graxos da carcaça de juvenis de trairão (Hoplias lacerdae). Utilizou-se o delineamento inteiramente casualizado, com sete tratamentos (0, 17,5, 52,5, 87,5, 122,5, 175 e 350 mg kg-1 de vitamina C na ração) e quatro repetições. Ao final de 62 dias, foram avaliados: ganhos de peso e comprimento, taxas de sobrevivência e canibalismo, uniformidade do comprimento final, sinais clínicos de excesso ou deficiência de vitamina C, presença de deformidades ósseas e perfil de ácidos graxos da carcaça. Peixes alimentados com a dieta isenta de vitamina C apresentaram maior uniformidade em comprimento final. Não foram detectadas deformidades no corpo dos peixes. As análises radiológicas confirmaram a ausência de deformidades ósseas. Observou-se efeito linear positivo dos níveis de vitamina C na dieta para os ácidos mirístico e araquidônico. Portanto, a vitamina C influencia o metabolismo de ácidos graxos da carcaça dos peixes. Durante o crescimento inicial de juvenis de trairão, a vitamina C não causa deformidades ósseas e não influencia o desempenho produtivo, porém afeta de forma negativa a uniformidade quanto ao comprimento final de juvenis de trairão.

The objective of this work was to evaluate the effect of diet supplementation with vitamin C on productive performance, morphological changes, and fatty acid profile of the carcass of juvenile giant trahira (Hoplias lacerdae). A completely randomized design was used, with seven treatments (0, 17.5, 52.5, 87.5, 122.5, 175, and 350 mg kg-1 of vitamin C in the diet) and four replicates. After 62 days, the following were evaluated: weight and length gains, survival and cannibalism rates, final length uniformity, clinical signs of excess or deficiency of vitamin C, the presence of bone deformities, and fatty acid profile of the carcass. Fish fed the diet without vitamin C showed higher final length uniformity. No deformities were detected in fish body. Radiological analysis confirmed the absence of bone deformities. A positive linear effect was observed in vitamin C levels in the diet for myristic and arachidonic acids. Therefore, vitamin C influences the metabolism of fatty acids in fish carcass. During the initial growth of juvenile giant trahira, vitamin C does not cause bone deformities and does not influence productive performance, but negatively affects uniformity as to the final length of juvenile giant trahira.

The objective of the present study was to evaluate the protein requirement of juvenile Trichogaster lalius, blue variety. The experimental design was of randomised blocks (B1 = initial weight of 1.04±0.05 g and B2 = 1.36±0.02 g), with two replicates within each block and five treatments (230, 270, 310, 350 and 390 g CP/kg diet). The fish were fed to satiation, three times a day for 90 days. The study evaluated: survival rate, weight gain, final length, feed intake, feed conversion ratio, protein efficiency ratio, specific growth rate and condition factor. There was a linear effect of dietary protein levels for protein efficiency ratio, specific growth rate (positive linear effect) and feed conversion ratio (negative linear effect). For weight gain, final length, feed intake and condition factor a quadratic effect of dietary protein levels was observed, with estimated values of 409.8, 366.2, 317.4 and 365.0 g CP/kg diet, to improve their performance parameters. Analysis of growth based on the length of the fish shows that 366.2 g of CP/kg diet meets the protein requirement of juvenile Trichogaster lalius, blue variety.

The study evaluated the replacement of bovine heart by gelatin in the feed training of carnivorous fish, using giant trahira (Hoplias lacerdae) as an experimental model. A completely randomized design with four treatments and five repetitions was employed. The treatments were composed of wet ingredients beef heart (control), gelatin diluted in water, gelatin diluted in beef heart broth, and gelatin diluted in water mixed with fish meal. The fish (3.22±0.03 cm and 0.57±0.01 g) were conditioned to accept industrialized diets by the technique of gradual feed ingredients transition in the diet. Gains in weight and length, efficiency of feed training, specific growth rate, cannibalism, mortality and survival rates were evaluated. There was significant difference in weight and length gains and specific growth rate, whereby the use of bovine heart gave the best results. Greater efficiency of feed training was observed for fish fed diets containing beef heart and gelatin diluted in water mixed with fish meal. The high survival rates and the absence of significant differences among treatments for rates of cannibalism, mortality and survival indicate the feasibility of using gelatin as a moist ingredient in the feed training of carnivorous fish.

The objective of this study was to investigate the effect of different water salinities on juvenile Hoplias lacerdae during feed training. Salinity levels of 0, 3, 6 and 9 g salt L-1 were used. Juveniles (3.33±0.1 cm and 0.6±0.09 g) were stocked at a density of six fish L-1 in aquaria (10 L volume) with supplementary aeration. Weight gain, length gain, and rates of survival, mortality, and cannibalism were evaluated after 20 days. Total mortality was observed in 0 g of salt L-1. The best survival rates of 98.7 and 97.5% were recorded in 3 and 6 g of salt L-1, respectively. The greatest weight gain was recorded in fish grown in 3 g of salt L-1 followed by fish grown in 6 g of salt L-1. Length gain was similar in the 3 and 6 g salt L-1 groups. No weight or length gain was recorded in 9 g of salt L-1. According to regression equations, the optimum water salinity was 5.15, 4.03 and 4.55 g of salt L-1 for survival rate, weight, and length gain, respectively. Salinity between 4.03 and 5.15 g of salt L-1 during feed training of juvenile giant trahira improves productive performance.

The aim of this study was to evaluate the influence of light intensity on the feed training of juvenile giant trahiras (Hoplias lacerdae). A completely randomized design with four light treatments and three replicates was used, and the following light intensities were tested: 204.9; 177.58; 54.64 and 0.00 lux. Juvenile giant trahiras (length = 3.0 ± 0.4 cm and weight = 0.5 ± 0.05 g) were stocked at 6 fish L-1 in 12 rectangular tanks (24 × 20 × 14 cm) containing six liters of water, and subjected to feed training to accept dry diets. At the end of the experiment (21 days), weight gain, length gain, survival, cannibalism, and mortality rates were evaluated. Data were subjected to regression analysis at 5% probability. Different light intensities did not affect growth, survival, mortality, or cannibalism rates in juvenile giant trahiras during the feed training. Therefore, this species can be trained to accept dry diets in the presence or absence of light.

Com este trabalho objetivou-se avaliar a suplementação de vitamina C durante a fase de condicionamento alimentar de alevinos de trairão. Um experimento foi estabelecido em delineamento inteiramente casualizado com sete tratamentos (0,0; 17,5; 52,5; 87,5; 122,5; 175,0 e 350,0 mg de vitamina C/kg de ração) e quatro repetições. Alevinos de trairão (2,8 ± 0,2 cm) foram distribuídos em aquários de 6 L, na densidade de 6 peixes/L. Uma ração basal foi confeccionada com 44,0% proteína bruta, e diariamente foi adicionada vitamina C e coração bovino. Após 20 dias, realizou-se biometria dos peixes para avaliação do ganho de peso e do comprimento, das taxas de sobrevivência e canibalismo e da uniformidade do comprimento final e para observações macroscópicas de sinais clínicos de deficiência ou excesso da vitamina. Após a biometria, dez peixes de cada dieta testada foram coletados para análise do perfil de ácidos graxos e este perfil foi comparado ao perfil de peixes, na mesma fase de vida, alimentados com peixes forrageiros coletados de viveiros de criação. Os dados de desempenho produtivo e perfil de ácidos graxos foram submetidos a análise de regressão polinomial e a uniformidade do comprimento final avaliada pelo teste de Bartlett. Houve diferença significativa apenas para a uniformidade em comprimento final e perfil de ácidos graxos da carcaça. A suplementação com 52,5 mg de vitamina C/kg de ração proporcionou maior uniformidade do comprimento final dos peixes. Os peixes dos viveiros de criação apresentaram menor concentração de PUFA (polyunsaturated fatty acids) e maior de ácidos graxos saturados em comparação aos peixes condicionados a aceitar dietas secas.

The objective of this work was to evaluate suplemenation of vitamin C during feed training of giant trahira fingerlings. An experiment was established in a complete random design with seven treatments (0.0, 17.5, 52.5, 87.5, 122.5, 175.0 and 350.0 mg vitamin C/kg diet) and four repetitions. Giant trahira fingerlings (2.8 ± 0.2 cm) were distributed in 6-L aquaria at the density of 6 fish/L. A basal diet was formulated with 44.0% of crude protein and vitamin C and bovine heart were added in it daily. After 20 days, biometry of fish for evaluation of weight and length gains, rates of survival and cannibalism and uniformity of final length and for macroscopic observations of clinical signs of deficiency or excess of vitamin was carried out. After biometry evaluation, ten fish from each tested diet were collected for analysis of the fatty acid profile which was compared to profile of fish at the same life stage fed forage fish collected from breeding fishponds. Data on growth performance and fatty acid profiles were submitted to analyses of polynomial regression and uniformity of the final length was evaluated by the Bartlett test. There was a significant difference only for uniformity in final length and fatty acid profile of the carcass. Supplementation with 52.5 mg vitamin C/kg diet provided a greater uniformity of the final length of the fish. Fish from breeding fishponds presented lower concentration of PUFA (polyunsaturated fatty acids) and higher concentration of saturated fatty acids compared to fish trained to accept dry diets.

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.