Freshwater fish are an important source of protein, but they also contain other highly nutritive components such as fats. Polyunsaturated fatty acids (PUFAs) are essential for normal growth, development and reproduction of vertebrates. The antioxidant role of vitamin E in cell membranes prevents fatty acid and cholesterol oxidation, thereby promoting PUFA and subcellular particle stabilization. The effects of vitamin E supplementation on the quality of Nile tilapia (Oreochromis niloticus) carcass were investigated. The experiments were carried out in an experimental laboratory over 106 d. After sex reversal, 400 early juvenile O. niloticus were tested in a completely randomized experiment with 5 treatments (4 repetitions each), consisting of vitamin E monophosphate supplementation at 0, 50, 100, 150 or 200 mg/kg of a base diet. Treatment diets contained equal amounts of protein and energy. Tilapias supplemented with vitamin E contained arachidonic acid (20:4 x-6; AA) which participates in inflammatory response. Nile tilapia carcasses that received vitamin E at 100 and 150 mg/kg diet had improved carcass quality by increasing the PUFA:SFA ratio and had the highest levels of polyunsaturated fatty acids from the omega-3 (linolenic acid; 18:3 x-3) and omega-6 (linoleic acid; 18:2 x-6) series.

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Some studies and scientific investments have been done in aquaculture aiming to minimize the stress of the fish due to different factors, as management, nutritional status, water quality, temperature, photoperiod, and salinity. This study aimed to verify the effect of photoperiod on locomotor activity and plasma levels of cortisol and glucose in female Lambari. One hundred and twenty female Lambari adult were maintained in aquaria of 20 liters each in a completely randomized design with three treatments (T1 = 0Light: 24Dark, T2 = 12L: 12D, T3 = 24L: 0D) and four replications. The daily locomotor activity was registered during 15 days using an infrared photocell. After 40 days of experiment and previous fasting for 24 hours, fish were euthanized by a lethal dose of benzocaine. Female Lambari featured a diurnal rhythm of locomotor activity. Lambari subjected to 12:12 and LD photoperiod presented higher cortisol (12L:12E: 190.00 ± 37.73 ng/mL e 24L:0E: 148.850 ± 32.77 ng/mL) and locomotor activity levels and also lower survival rates (30.0 ± 7.07%) when compared to the LD photoperiod (cortisol: 85.570± 7.99 ng/mL, survival rates: 72.5± 4.330%). The glucose concentration (32.167 ± 22.73 mg/dL) and the growth (7.050±0.59cm) of fish subjected to LD photoperiod was significantly lower than in the other treatments. We conclude that light plays an important role in the growth, behavior and welfare of female Lambari. Besides, our data highlighted that fish submitted to a long light period present a more stressed and more aggressive status when compared to fish submitted to a continuous darkness.Index terms: Fish, synchronizer, glucose, cortisol, swimming behaviour. RESUMOAlguns estudos científicos e investimentos têm sido realizados na aquicultura com o objetivo de minimizar o estresse dos peixes, por diversos fatores, como a gestão, a salinidade do estado nutricional, qualidade da água, temperatura, fotoperíodo e salinidade. Este trabalho teve como objetivo verificar o efeito do fotoperíodo na atividade locomotora e níveis plasmáticos de cortisol e glicose em fêmeas de lambari. Cento e vinte fêmeas de lambaris adultas foram mantidas em aquários de 20 litros cada um, em delineamento inteiramente ao acaso, com três tratamentos (T1 = 0 Luz:24 Escuro, T2 = 12L:12E, T3 = 24L:0E) e quatro repetições. A atividade locomotora diária dos lambaris foi registrada durante 15 dias por meio de uma fotocélula infravermelha. Após 40 dias de experimento os peixes, mantidos a jejum de 24 horas, foram previamente anestesiados com benzocaína. As fêmeas de lambaris apresentaram um ritmo de atividade locomotora diurna. Lambaris submetidos aos fotoperíodos 12L:12E e 24L:0E apresentaram maiores níveis de cortisol (12L:12E: 190.00 ± 37.73 ng/mL e 24L:0E: 148.850 ± 32.77 ng/mL) e atividade locomotora, além de menores taxas de sobrevivência (30,0 ± 7,07%) em relação ao regime de 0L:24E (cortisol: 85.570± 7.99 ng/mL, taxa de sobrevivência: 72.5± 4.330%) A concentração de glicose (32.167 ± 22.73 mg/dL) e o crescimento (7.050±0,59cm) dos peixe...

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ABSTRACT. Minimization of stress during the transportation of live fish is essential in maintaining the welfare and performance of the animals. In order to test the hypothesis that stress during transport of fingerlings of Nile tilapia (Oreochromis niloticus) can be reduced with the aid of the anesthetics menthol, eugenol or benzocaine, we have assessed the effects of these agents at various concentrations on the physiological parameters and survival rates of fish subjected to conditions simulating those normally used in transportation. , maintained levels of plasma cortisol and glucose that were lower than those of the stressed but untreated controls and within the physiological limits of the baseline values for this species. Under these conditions, the survival rate was 100%, suggesting that stress was substantially reduced despite dense consignment. Treatments involving higher doses of the studied agents induced significant anesthetic toxicity. , mantiveram níveis de cortisol no plasma e de glucose que foram menores do que os dos controles não tratados e estressados, mas dentro dos limites fisiológicos dos valores da linha de base para esta espécie. Sob estas condições, a taxa de sobrevivência foi de 100%, o que sugere que o estresse foi substancialmente reduzido, apesar da remessa densa. Os tratamentos que envolvem doses mais elevadas dos agentes estudados induzindo uma toxicidade anestésica mais significativa.Palavras-chave: mentol, bezocaína, eugenol, peixe.

ABSTRACT. Rotation and translation of the Earth subject the living organisms to cyclic changes of environmental factors. This study evaluated the effects of photoperiod on growth and gonadal development in Nile tilapia (Oreochromis niloticus). In a completely randomized design experiment, juvenile males were distributed into nine tanks (10 fish per tank) and maintained for 60 days under three different light treatments with three repetitions each. The treatments were: T1 -0 h photoperiod (tanks covered with lids and black plastic); T2 -12 hours photoperiod (tanks uncovered during photoperiod to provide natural light); and T3 -24 hours photoperiod (tanks covered with lids equipped with lamps). No significant differences were found between treatments for body length, gonad weight or gonadosomatic index, but body weight was higher in fish subjected to T3 compared with other treatments. Furthermore, significant increases in tubular lumen and germinal epithelium were observed in fish exposed to T1 and T3, respectively. Thus, the manipulation of photoperiod in Nile tilapia culture systems can improve production and consequently increase the economic return on investment.Keywords: fish, testicular development, light, dark.Efeito do fotoperíodo sobre o crescimento e o desenvolvimento gonadal em macho de tilápia do Nilo RESUMO. Rotação e translação da Terra submete os organismos vivos a alterações cíclicas de fatores ambientais. Objetivou-se avaliar o efeito do fotoperíodo no crescimento e desenvolvimento gonadal em tilápia do Nilo (Oreochromis niloticus). Em um delineamento experimental inteiramente casualizado, machos jovens foram distribuídos entre nove tanques (10 peixes por tanque) e mantido por 60 dias sob três tratamentos de luz diferentes, com três repetições de cada um. Os tratamentos foram: T1 -0h de fotoperíodo (tanques cobertos com tampas e folhas de plástico preto); T2 -12h fotoperíodo (tanques descobertos durante o fotoperíodo para fornecer luz natural); e T3 -24h fotoperíodo (tanques cobertos com tampas equipados com lâmpadas). Não foram observadas diferenças significativas entre o tratamento em relação ao comprimento do corpo, peso das gônadas ou índice gonadossomático, mas o peso corporal foi maior nos peixes submetidos a T3 em comparação com outros tratamentos. Além disso, aumentos significativos na lúmen tubular e epitélio germinal foram observadas em peixes expostos a T1 e T3, respectivamente. Assim, a manipulação do fotoperíodo em sistemas de cultivo de tilapia do Nilo pode levar a uma melhora na produção e, consequentemente, a um aumento no retorno econômico sobre o investimento.