Success! I was able to find and eat fermented Greenland shark

The flesh of a Greenland shark is poisonous when fresh. This is due to the presence of the toxin trimethylamine oxide, which, upon digestion, breaks down into trimethylamine, producing effects similar to extreme drunkenness. Occasionally, sled dogs that end up eating the flesh are unable to stand up due to the neurotoxins. However, it can be eaten if it is boiled in several changes of water or dried or rotted for some months in a process known as Hákarl (as by being buried in boreal ground, exposing it to several cycles of freezing and thawing). It is considered a delicacy in Iceland and Greenland. View all photos here.