Anesthetic induction and recovery time of Centropomus parallelus exposed to the essential oil of Aloysia triphylla/ Inducao e recuperacao anestesica de Centropomus parallelus expostos ao oleo essencial de Aloysia triphylla

This study analyzed the effectiveness of the essential oil of Aloysia triphylla (EOA) as an anesthetic and stress reducing agent in the transport of fat snook (Centropomus parallelus). Juveniles were exposed to different concentrations of EOA (seawater-adapted: 25-300 µL [L.sup.-1]; freshwater-adapted: 200 µL [L.sup.-1]) to identify the anesthetic induction and recovery times. In an additional experiment, seawater-adapted fat snook were transported in plastic bags with 10 or 20 µL [L.sup.-1] EOA for 6 or 24h. The increased concentration of EOA proportionally decreased the time required for anesthesia induction. Mortality was 30 and 70% in fat snook transported with 10 and 20 µL [L.sup.-1], respectively, 24h after transport. The addition of 20 µL [L.sup.-1] EOA significantly reduced plasma cortisol levels during transport compared to the control group, but increased blood glucose levels after 6 and 12h of transport. The EOA reduced total ammonia and dissolved oxygen levels at the end of transport compared to control fish. The EOA is recommended for sedation (25-50 µL [L.sup.-1]) and anesthesia (100-300 µL [L.sup.-1]) but not for transport of fat snook because it increased mortality. Key words: anesthesia, blood parameters, fat snook, natural product, transport. Este estudo verificou a eficacia do oleo essencial de Aloysia triphylla (OEA) como um anestesico e redutor de estresse no transporte de robalo-pevas (Centropomus parallelus). Os juvenis foram expostos a diferentes concentracoes de OEA (adaptados a agua do mar: 25-300 µL [L.sup.-1]; adaptados a agua doce: 200 µL [L.sup.-1]) para identificar os tempos de inducao e recuperacao da anestesia. Em um experimento adicional, robalos-peva adaptados a agua do mar foram transportados em sacos plasticos com 10 ou 20 µL [L.sup.-1] OE por 6 ou 24h. O aumento da concentracao do OEA diminuiu proporcionalmente o tempo necessario para a inducao da anestesia. A mortalidade foi de 30 e 70% em robalo-pevas transportados com 10 e 20 µL [L.sup.-1], respectivamente, 24h apos o transporte. A adicao de 20 µL [L.sup.-1] OEA reduziu significativamente o cortisol plasmatico durante o transporte, comparado ao grupo controle, mas aumentou os niveis de glicose sanguinea apos 6 e 12h de transporte. O OEA reduziu os niveis de amonia total e de oxigenio dissolvido ao final do transporte em comparacao com o grupo controle. O OEA e recomendado para sedacao (25-50 µL [L.sup.-1]) e anestesia (100-300 µL [L.sup.-1]), mas nao para o transpor