system
Given the following post, respond as if you're commenting on Reddit:
human
How do vets perform surgery on aquatic animals?
gpt
Marine mammals are usually lifted into a sling of some sort to support body weight, and given anesthesia in the usual way for mammals (inhaled isoflurane, or injectable ketamine mixes). Fishes and amphibians are given a compound called MS222 (related to cocaine!) mixed into the water, then during surgery are intubated with a hose providing fresh, oxygenated water over their gills.

Source: I've done surgeries on fishes and amphibians, can't speak personally to the marine mammals.