Safety of AQUI‐S 20E (10% Eugenol) as a Sedative for Freshwater Fish

AQUI‐S 20E (10% eugenol) has been shown to be an effective fish sedative for freshwater finfish, but to be approved for use in the United States, the U.S. Food and Drug Administration must be provided with data demonstrating the product is safe to treated animals. Accordingly, we evaluated the safety of AQUI‐S 20E when used to sedate Rainbow Trout Oncorhynchus mykiss , Yellow Perch Perca flavescens , and Channel Catfish Ictalurus punctatus . After identifying the highest effective concentrations likely to be used by fisheries biologists to sedate each species to handleable, replicate groups of fish were exposed to this intended concentration (1×) or a 50% higher eugenol concentration (1.5×) for periods of time adequate to effectively sedate 80% of fish to handleable (ET80) or for predetermined treatment periods exceeding the ET80. These predetermined treatment doses (40 and 60 mg eugenol/L for Rainbow Trout, 80 and 120 mg eugenol/L for Yellow Perch, and 100 and 150 mg eugenol/L for Channel Catfish), treatment periods (2.25–8.75 min for Rainbow Trout, 4.0–10.5 min for Yellow Perch, and 2.5–12.0 min for Channel Catfish; specific treatment periods depending on doses), and ET80 values were used to establish margins of safety for each species. An adequate margin of safety was defined as treatment periods ≥ 3–4 min longer than the 1× ET80 and ≥ 2–3 min longer than 1.5× ET80 after which fish survival was ≥ 95%. Based on survival, there was an adequate margin of safety associated with overexposing fish to AQUI‐S 20E. Given the absence of biologically relevant effects of AQUI‐S 20E exposure on tissue histology, there is no evidence to suggest that the survival‐based margins of safety should be revised to be more conservative. Our results indicate there is an adequate margin of safety associated with the use of AQUI‐S 20E to sedate freshwater fish to handleable. Received September 27, 2016; accepted December 27, 2016 Published online March 15, 2017