RESUMO Óleos essenciais vêm sendo intensamente utilizados em diversas aplicações comerciais, dentre elas como anestésicos. Avaliou-se o efeito de soluções com óleos extraídos de quatro tipos vegetais (melaleuca, cravo, eucalipto e menta) na sedação, na recuperação e no comportamento de estresse de tilápia-do-Nilo. Utilizaram-se soluções sedativas (óleo essencial:etanol, 1:4) na água de manejo dos peixes na dosagem de 7,4 mL/L sob delineamento inteiramente casualizado, com quatro tratamentos e sete repetições. Os resultados foram submetidos ao teste Scott-Knott (P < 0,05). De acordo com os resultados, o mais indicado para a imobilização de tilápia-do-Nilo é o óleo de cravo, no entanto as observações comportamentais indicam o óleo de melaleuca como o mais eficiente na redução do estresse.

ABSTRACT 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.

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 ºC 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).

Este trabalho foi conduzido com o objetivo de avaliar a utilização de fertilizantes - fosfato bicálcico, biossólido e fezes de codorna - na água de produção de Daphnia sp. Foram utilizados 24 tanques de cimento-amianto, cada um com volume útil de 100 L, em um delineamento inteiramente ao acaso em parcelas subdivididas com seis repetições, tendo nas parcelas os tipos de fertilizantes e um controle, sem adubação, e nas subparcelas as épocas de avaliação (dias 8 e 13). Foram avaliados a produção da biomassa de Daphnia sp. e os seguintes parâmetros de qualidade da água: clorofila a, condutividade elétrica, pH, oxigênio dissolvido, temperatura, nitrogênio amoniacal e orgânico, fósforo total e dureza total. Observou-se correlação significativa entre os valores de clorofila a e o peso da biomassa de Daphnia sp., o que indica interação entre as comunidades fito e zooplanctônicas. O peso máximo da biomassa de Daphnia sp. em tanques adubados com fezes de codorna é maior (35,98 g) que em tanques adubados com biossólido (16,80 g), sem adubação (6,75 g) ou adubados com fosfato bicálcico (5,24 g).

The current study was aimed at investigating the use of different fertilizers - dicalcium phosphate, biosolid and quail feces - as a strategy for water fertilization in Daphnia sp production. It was used twenty-four 100-L tanks of asbestos cement distributed in a completely randomized split-plot design with six replicates, with plots in the three kinds of fertilizers (biosolid, dicalcium phosphate, and quail feces) and a control without fertilization (WF) and subplots at the times of assessment (days 8 and 13). It was assessed the biomass production of Daphnia sp. and the following water quality parameters: chlorophyll a, electrical conductivity, pH, dissolved oxygen, temperature, ammonia and organic nitrogen, total phosphorus and total hardness. There was a significant correlation between the values of chlorophyll a and biomass weight of Daphnia sp, which indicates interactions between phytoplankton and zooplankton communities. The maximum weight of Daphnia sp. biomass is found in tanks fertilized with quail feces (35.98 g), followed by the biosolid (16.80 g), control without fertilization (6.75 g) and dicalcium phosphate (5.24 g).