The anesthetic activities of the essential oils (EOs) of Hesperozygis ringens (EOHR) and Lippia alba (EOLA) and their effects in silver catfish (Rhamdia quelen) after anesthesia and recovery were investigated. Fish (32.19 ± 1.24 g) were submitted to one of the following treatments for each EO: basal group, control, or anesthesia (150, 300, or 450 μL L(-1) EO). After that the anesthesia was induced or simulated and the biometric measurements were completed, fish were transferred to anesthetic-free aquaria to allow for recovery. Fish were sampled at 0, 15, 30, 60, and 240 min after recovery. At time 0 of recovery, the ventilatory rate was lower in the groups anesthetized with either EO. In comparison with the basal group, control fish showed an increase in plasma glucose, aspartate aminotransferase (AST), and Na(+) levels and a reduction in Na(+)/K(+)-ATPase activity at 0 min of recovery. Plasma levels of ammonia and Na(+) were lower in the fish anesthetized with EOLA (450 μL L(-1)) and EOHR (all concentrations), respectively, than in the control fish. Additionally, lactate, AST, alanine aminotransferase, K(+) plasma levels, and gill Na(+)/K(+)-ATPase and H(+)-ATPase activities were higher in the fish anesthetized with either EOHR or EOLA than in the control fish. The EOs promoted slight changes in silver catfish that enabled both an adaptive response and the recovery of most of the measured parameters after 240 min regardless of concentration or EO that was used. These findings support the use of EOHR and EOLA as anesthetics for fish.

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This study evaluated the seasonal influence on the yield and chemical composition of the essential oil (EO) of Nectandra megapotamica. Fresh young (YL) and old leaves (OL) obtained from three trees in each season (Nov/2010 to Sep/2011

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This study evaluated anesthetic efficacy and possible effects of the essential oils (EOs) of Cunila galioides (EOC) and Origanum majorana (EOO) on ventilatory rate (VR) and ionoregulation in Rhamdia quelen. In the anesthesia assessments, 50, 100, 200 and 300 μL L -1 EOC and 50, 100, 200, 300, 400 and 500 μL L -1 EOO were tested, and time for induction to sedation and anesthesia stages, as well as recovery, were taken. A second trial employed lower concentrations of both EOs, 10, 25, 50 and 100 μL L . There was no significant difference between control and EO-treated groups regarding VR, but all fish subjected to 100 µL L -1 EOC died within 2 h of exposure. Overall, ionic loss declined in the presence of the EOs. The EOC at 200 -300 μL L -1 and EOO at 400 -500 μL L -1 present the potential to promote fast anesthesia in R. quelen.