Fred is a greenish-brown fish (sometimes blue, gray or bright purple) who was the first of the generic background character models to appear in the series. He is best known for screaming "My leg!" in certain situations.
In most episodes, he appears as a greenish-brown colored fish with light tan fins and black eyes. He wears brown pants and a black belt with a gold colored belt buckle.
His first appearance is the episode "Reef Blower." However, he is barely seen in the episode, as he is in a boat as SpongeBob zooms past him. He's most often seen dining at the Krusty Krab. He was one of the first two background characters, and Harry was the other.
His name is revealed in the episode "Patty Hype," where he is advertising the Shell Shack's talking and singing dog.
He is famous for the running gag in which he screams his catchphrase, "My leg!", when something such as an explosion takes place. He first says it in the episode "Boating School."