For some reason, they aggro Kairukus (Penguins) when in the wild. Aberrant versions can and will attack you in surface waters as well, learned that they aggro Kairukus by summoning an Aberrant Angler and then a Kairuku in front of it then it aggroed it! (The Kairuku was wild)
It seems there is a strange circular underwater hill near herbivore island that is apsolutely crawling with anglers, how many does that mran? Well I've seen about the entire rest of the ocean's population of anglers all at that hill
They spawn a lot in the Ice Cave on the Island. Since they’re in a cave they respawn fast too. My tribe leader made it out of there with multiple stacks of angler gel. It was actually starting to encumber him.