Essential oil of citronella modulates electrophysiological responses in tambaqui Colossoma macropomum: A new anaesthetic for use in fish

• Published in: Aquaculture Vol. 479; pp. 60 - 68
• Main Authors: Barbas, Luis André Luz, Hamoy, Moisés, de Mello, Vanessa Jóia, Barbosa, Ruan Paulo Melo, de Lima, Hildado Socorro Trindade, Torres, Marcelo Ferreira, do Nascimento, Luis Adriano Santos, da Silva, Joyce Kelly do Rosário, Andrade, Eloísa Helena de Aguiar, Gomes, Madson Ralide Fonseca
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01-10-2017
• Subjects: Citronellol; Electrocardiography; Electromyography; Geraniol; Respiratory frequency; Sedation; Respiratory frequency; Electrocardiography; Citronellol; Electromyography; Sedation; Geraniol
• ISSN: 0044-8486; 1873-5622
• DOI: 10.1016/j.aquaculture.2017.05.027

The aim of this study was to evaluate the efficacy of essential oil of citronella, Cymbopogon nardus (EOC) as an anaesthetic for fish, using juvenile tambaqui Colossoma macropomum as a model. The times to induction and recovery after short-term anaesthesia were evaluated by concentration-response trials. Moreover, electrophysiological responses in muscle (EMG), electrocardiographic data (ECG), opercular beat intensity (OBI) and rate (OBR) were also evaluated. Juveniles were placed in aquaria containing six concentrations of EOC (200, 400, 600, 800, 1000 and 1600μLL−1) and the times of anaesthetic induction and recovery were registered. Sham control fish and fish exposed to ethanol-added water were used as controls. With the exception of the lowest concentration used (200μLL−1), deep anaesthesia was attained at all other subsequent concentrations, being the use of 600μLL−1 sufficient to promote rapid induction (<3min) and uneventful recovery (<5min) from deep anaesthesia; while the concentration of 200μLL−1 was sufficient to induce sedation. EOC elicited a conspicuous depression on muscle contraction power with loss of muscle tonus. Although transient cardiorespiratory depression occurred during deep anaesthesia, gradual increases in the amplitudes of the differences in potential and frequencies in EMG, OBI and ECG, corroborate the reversibility and smooth transition to normal swimming behaviour during recovery from anaesthesia with EOC.
•Essential oil of citronella, Cymbopogon nardus induced deep anaesthesia and calm recovery in juvenile Colossoma macropomum.•This oil promoted muscle relaxation in fish submitted to short-term baths.•Cardioventilatory function was not compromised during deep anaesthesia with this oil.•This is first study using behavioural and electrophysiological analyses to evaluate anaesthesia in fish.