Melody Danley

Date of Graduation


Document Type



There is need for an anesthetic to sedate fishes that does not require a mandatory post-exposure withdrawal period. Such an anesthetic could be used to sedate handled fishes as they are moved from tank to tank on the farm, surveyed in the wild, released from state and federal hatcheries, or harvested for human consumption. A proprietary form of clove oil, AQUI-S® , was recently submitted to the U.S. Food and Drug Administration for approval as a 0-day withdrawal anesthetic for use on aquatic organisms. As part of the approval process, a large series of efficacy and toxicity studies are required. The purpose of the following research was to evaluate effective anesthetic concentrations (loss of equilibrium or complete anesthesia in approximately 10 min or less) for three species of fish from the U.S. Bureau of Reclamation Tracy Fish Collection Facility in Tracy, California and to evaluate the 96-h post-exposure survival of those exposed fish to a standard dose for up to 60 min. The three species tested were Sacramento splittail (Pogonichthys macrolepidoctus), Sacramento perch ( Archoplites interruptus), and threadfin shad (Dorosoma petenense ). The current research found effective AQUI-S® concentrations to be similar to those reported by the manufacturer and by other studies (50–80 mg/L to induce loss of equilibrium and complete anesthesia), although some effective concentrations required slightly longer than 10 min to induce complete anesthesia (species dependent). Anesthetic concentrations that induced loss of equilibrium in approximately 10 min or less were 45 mg/L, 60 mg/L and 20 mg/L for Sacramento splittail, Sacramento perch, and threadfin shad, respectively. The current research identified potential limitations in use of AQUI-S® (exposure time vs. survival), which is to be expected for any drug that affects the physiological functions of a living organism. Splittail 96-h survival was significantly affected when exposed to 50 mg/L for 60 min, while exposures up to 40 min did not significantly affect survival (α= 0.05). Sacramento perch showed no significant differences in 96-h survival when exposed to 50 mg/L AQUI-S® for up to 60 min, compared to the control. Finally, threadfin shad 96-h survival decreased significantly with increasing exposure time when exposed to 70 mg/L.