The use of anesthetics has facilitated a variety of important procedures in fisheries research. These procedures include mak-ing measurements, administering tags, extracting tissue samples,and minor surgery. When properly applied, anesthesia calms thefish, reduces its movement, and minimizes stress and pain. Theseattributes increase researchers’ ability to handle fish without injur-ing themselves or the fish. Furthermore, anesthesia is required byInstitutional Animal Care and Use Committees (IACUC) following guidelines of the Association for Assessment and Accreditation ofLaboratory Animal Care International (AAALAC) and regulation sprovided by the Animal Welfare Act (Garber et al., 2011).Many different methods of anesthetization have been tested on fishes, but technical or legal reasons limit applications in the field.When tagging or surgery is involved, stage-4 anesthesia should bein duced, which is characterized by complete loss of equilibrium,loss of swimming motion, and weakened opercular movements∗