No abstract

-The experiment was performed with 160 tambaqui (Colossoma macropomum) with average weight 11.01±2.08 g and total length 7.8±0.18 cm. Fishes were kept in sixteen aquariums with 56 L of water at 29.1±0.4 o C of temperature, initial stocking density 1.97 g/L and constant aeration. The objective of this study was to assess the influence of photoperiod on fish performance. Treatments consisted of four photoperiods: T1 = 6 hours; T2 = 12 hours; T3 = 18 hours and T4 = 24 hours, with four replicates each. Fishes were fed twice a day with commercial extruded feed (28% of crude protein).The experiment was developed in closed circulation system, with volume of water renewal for each experimental unit equivalent to 40 times daily. Fish biometry was performed at the beginning of the experiment and at every 16 days, in order to follow the effects of treatments on juvenile development. Final weight, total length, standard length, height, feed intake, weight gain, feed conversion, survival, specific growth rate, protein efficiency rate and protein retention efficiency were assessed.Statistical analysis of variables was performed with application of the software SAEG version 9.1, for analysis of variance, regression analysis and Pearson correlation. Positive influence of photoperiod was observed for the studied variables in this study. The studied variables enhanced as the photoperiod increased, mainly between 15 and 22 hours. The photoperiod has significant influence upon growth traits of tambaqui (Colossoma macropomum).

-Essential oils have been extensively used in many commercial applications, one of them being anesthetics. The effect of four essential oils (tea tree, clove, eucalyptus, and mint oils) on the sedation, recovery, and behavioral stress of Nile tilapia (Oreochromis niloticus) was evaluated. The sedative solutions, prepared with essential oils and anhydrous ethanol (1:4), were used for fish management procedures at a dose of 7.4 mL L -1 in a completely randomized block design with four treatments and seven replicates. The means were compared using Scott-Knott test (P < 0.05). Clove oil was found to be the most suitable oil for the immobilization of Nile tilapia; however, behavioral observations indicate that tea tree oil was the most efficient in reducing stress. Keywords

ABSTRACT.-Muzitano I.S., Neves C.A., Radael M.C., Rezende F.P., Mendonça P.P., Santos M. Farmed fishes are highly sensitive to diets deficient in ascorbic acid with clinical symptoms that affect performance and commercialization for causing deformities. Aiming to meet the minimum levels for red rainbow fish, six isoaminoacid and isocaloric diets with varying levels of active vitamin C were tested. At the end of 42 days experimental period, 36 fishes were histologically analyzed for the percentage of connective tissue and muscle fibers in order to determine the influence of the Vitamin C percentage in those ratios. Although the averages are statistically indistinguishable from the quantitative point of view, qualitatively higher levels of vitamin C allow better tissue structure. The breakdown of muscle tissue is indicative for dietary deficiency of ascorbic acid.INDEX TERMS: Ascorbic acid, Glossolepis incisus, ornamental fish, fish farming, collagen.