Well, I've fished this place for the last five years and it keeps getting worse and worse. I think it's Skunk, the three-eyed giant catfish, that keeps scaring everything away from my spot.”— Fisherman
The giant catfish is a sea creature mutated from the common pre-War catfish.
The giant catfish is only mentioned in-game by a fisherman in Fallout. A humanoid, mutated catfish known as a "catfish mirelurk" also appears in The Art of Fallout 3, the art book available with the collector's edition of Fallout 3.