Angler fish have the bright antenna, so look out for that whe. Trying to locate one.

There tend to be quite a lot of angler spawns in North zone near Carno Island

The dilophosaurus of the seas...

Anglers are found in the deeper parts of the ocean, finding them is as one would guess easy as their lures are easy to see at a distance, they are comparatively easy to kill for gel ( taming food for Mantas and the best fuel in game ) but in groups exceeding three then I suggest running, best take a megaladon.
Also can be lured by other tamed anglers lures.

The terror birds of the sea the are extremely annoying just like the terror birds on land