The anaesthetic-like effect of tea tree oil in common carp Cyprinus carpio L.

This study investigated the efficacy of tea tree oil (TTO) as an anaesthetic for common carp, Cyprinus carpio L., by estimation of behaviour changes and responsiveness to being taken out of the water. All applied concentrations (from 0.2 to 0.6 mL L−1) resulted in sedation and immobilization. The lowest effective concentration (induction time ≤3 min, recovery time ≤10 min after 15 min of exposure) was 0.5 mL L−1. Exposure in excess of 30 min at a concentration of 0.5 mL L−1 caused mortality. TTO displayed distinct general anaesthetic-like properties, fulfilling the basic requirements for a potent fish anaesthetic.