\:\) It was the word. I didn't choose it for ugliness' sake.
If you take a look at zmjezhd's link the monk they thought the fish looked like is equally ugly. (Thanks for that link, zmjehzd)).
A somewhat farfetched resemblance , but they may have had Savonarola in mind who was actively brandishing sinners a little before that time and was as ugly as a monkfish indeed.

Savonarola

Well, that monk ended up fried like a monkfish.