Short CommunicationCarbon dioxide is an effective anesthetic for multiple marine fish species

•Carbon dioxide enriched sea water induced stage-4 anesthesia in five marine fishes.•Fishes were induced to stage-4 anesthesia in <10 min and recovered in <5 min.•Across all species, induction time was related to size.

Fisheries research involving surgery is aided by, and sometimes requires, anesthesia, but health and safety regulations limit the anesthetic methods that can be used on species considered food fish. Carbon dioxide is one anesthetic that the United States Food and Drug Administration (FDA) tolerates when certain guidelines are met, and it complies with Institutional Animal Care and Use Committee protocols. But, there is very little published work that characterizes this compound's utility on marine fishes and no studies have compared its effectiveness across species or sizes. We used acetic acid and sodium carbonate to create a carbon dioxide rich sea water bath to induce anesthesia and measured induction time and recovery time for five species and several sizes of marine fishes. We found that carbon dioxide quickly and effectively anesthetized these marine fishes to stage-4 anesthesia, a level acceptable for minor surgery. Induction time was positively related to body size (total length or wet mass), but recovery time was independent of size. Using red drum, we also found differences between rested and fatigued individuals. These results provide needed documentation of the effectiveness of carbon dioxide on marine fishes and are useful for planning field studies that involve minor surgery on marine food fish.