At first, the cave fisher seems like just another ambush predator, pretty much interchangeable with other low-level dungeon dangers. But it’s also a primer in how to create a classic monster: a simple but evocative name, a unique attack, and a place in the dungeon ecology that makes sense. Which is why it keeps creeping back into role-playing, edition after edition.
A river route used by smugglers is said to be haunted by a ghost who pulls men from their boats. Actually a cave fisher has taken up residence in the catacombs.
Pechs are too clever and too powerful in earth magic to fear cave fishers, but they sometimes encourage one to settle near their lairs to serve as a line of defense. Svirfneblin, on the other hand, exterminate them. Mongrelmen often need the help of adventurers, whom they reward with carefully collected secrets.
In the tropics, cave fishers don’t always remain in caves. Palms and mangroves can hide a subspecies of cave fisher whose mottled hide provides excellent camouflage (Stealth +6).
—Pathfinder Bestiary 41