Sedative and anesthetic efficacy of the essential oils from the Brazilian native plants Pilocarpus pennatifolius and Cordia verbenacea in Nile Tilapia.

This study aimed to evaluate the effectiveness of essential oils (EO) of Pilocarpus pennatifolius (PPOL) and Cordia verbenacea (CVOL) as sedatives and/or anesthetics in juvenile Nile tilapia (Oreochromis niloticus). The main constituents of PPOL were 2-undecanone (57.2%) and 2-Tridecanone (28.3%), and of CVOL α-pinene (34.8%), which were determined by gas chromatography. PPOL led juveniles to sedation at concentrations of 2 (703.8s), 10 (407.4s), 20 (225.5s), 50 (190.2s), and 80 (163.5s) mg L-1. CVOL also induced sedation at these concentrations, with times of 504.9, 294.2, 142.8, 113.8, and 135.6 s, respectively. Both EOs at 200 mg L-1 induced deep anesthesia within 507.5 (PPOL) and 1267.7 s (CVOL). Exposure to PPOL at 2, 20, and 80 mg L-1 for 48 h resulted in fish sedation, while CVOL lead fish to sedation at the two lowest concentrations and anesthesia at the highest one. Possible stress responses were evaluated during anesthetic recovery and long exposure, and PPOL did not cause behavioral or glucose levels changes in all evaluations. However, CVOL increased glucose levels at the highest concentrations studied (80 and 200 mg L-1), indicating that this oil may have caused stress in fish.