Clove Oil as an Anesthetic for Invasive Field Procedures on Adult Rainbow Trout

Abstract

Clove oil has recently been proposed as an appropriate anesthetic for researchers to use on food fish; however, its use in invasive procedures has not yet been reported for salmonids. In a telemetric investigation, we found the concentration of clove oil required for invasive procedures to be 30 mg/L, which is 75% less than previously suggested dosages to achieve and maintain a level of deep anesthesia in adult rainbow trout Oncorhynchus mykiss (N = 20). Mean time (±SE) to achieve level 4 anesthesia was 3.7 ± 0.9 min. Average exposure time to the anesthetic (surgery time) was 5.8 ± 0.2 min, and average recovery time (the time required to regain equilibrium and full swimming mobility) was 4.9 ± 1.0 min. Lengthy recovery times (up to 18 min) were observed; such times are typically reported for clove oil. Field investigators should conduct preliminary trials to determine the appropriate concentration of clove oil for their conditions, particularly if the application requires more than 5 min of exposure to the anesthetic.