Skunk

The giant catfish is an aquatic creature mentioned in Fallout.

Background
According to a California fisherman, in 2161, a three-eyed giant catfish he calls "Skunk" keeps scaring other fish away from his spot.

Appearances
The giant catfish is only mentioned in-game by a fisherman in Fallout.

Behind the scemes
A catfish mirelurk appears in concept art in The Art of Fallout 3.