Are Better Anesthetics Needed in Fisheries?

Abstract

Federal, state, and private fishery workers were asked which anesthetics they used and for which fish species; how the materials were used; the disadvantages or problems associated with their use; and the desired characteristics of an ideal anesthetic. Responses were received from 66 state or provincial hatcheries, 40 federal hatcheries, 3 private hatcheries, and 74 others who did not identify themselves by category. Tricaine methanesulfonate (MS-222) was by far the most commonly used anesthetic (145 users), followed by quinaldine (41), and carbon dioxide (18). Carbon dioxide and MS-222 are the only registered fish anesthetics. The most cited limitation on the use of MS-222 was the 21-day withdrawal period required after treatment. The ideal anesthetic should permit a reasonable duration of exposure, produce anesthesia within 3 minutes or less, allow recovery within 5 minutes or less, cause no toxicity to fish at treatment levels, present no mammalian safety problems, and leave low tissue residues after a withdrawal time of 1 hour or less.