You may be aware that, in some languages, fish is known as 'poisson'. Notice how 'poisson' is one letter shy of 'poison'? There's a reason for that: all fish carry varying amounts of poison in their bodies. Cooking can help to remove some of that poison, but certain varieties of raw fish are extremely dangerous to eat.
A chunk of raw monkfish is not only delicious to other fish, but extremely poisonous. It makes it an angler's dream: a little glob of angry meat that can attract and then kill some of the most desirable fish.