Drug Research Information Bulletin - Use of AQUI-S®20E, Tricaine-STM, and AQUACALMTM to Sedate Rainbow Trout to Handleable

Fish sedatives are used to achieve various stages of sedation (Summerfelt and Smith 1990) to facilitate fisheries research and management, such as “light sedation” for transportation, “loss of equilibrium” for routine handling, and “deep sedation” for surgical procedures. Although numerous chemicals have been evaluated for their utility as fish sedatives, only Tricaine-STM (tricaine methanesulfonate, tricaine, or MS222; Syndel USA., Ferndale, Washington USA) is approved by the U.S. Food and Drug Administration (FDA) as a fish sedative/anesthetic and available in the U.S. Tricaine-STM is approved for temporary immobilization of ictalurid, salmonid, esocid, and percid fishes. Tricaine-STM is effective and widely used by fisheries professionals throughout the U.S.; however, a 21-day withdrawal period is required for treated fish that may enter the human food supply through stocking or slaughter. For many field applications, holding fish for 21 days post-sedation is not practical and may seriously compromise management or research activities.