His character model appears lavender in "The Sponge Who Could Fly" and blue in numerous other episodes (e.g. "Something Smells"). Although the sclera of his eyes are usually white, they are yellow in "The Inmates of Summer."
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 seen in "Reef Blower," with Harry being the other.
He is the protagonist in the episode "My Leg!" where he tries not to hurt his leg in risk of getting it placed by a robotic leg. SpongeBob then tries to keep Fred's leg out of harm's way until he finally reveals that he likes to be in the hospital so he can be with Nurse Bazooka (a nurse he is secretly in love with). So SpongeBob helps Fred by doing many dangerous attempts to purposely hurt his leg, but they just keep failing. When Fred finally ended up in the hospital (after getting ran over by the ambulance twice), he sings the song "My Leg is in Love " to show Nurse Bazooka how much he loves her. She enjoys the song and the two end up dating. This episode is Fred's biggest role yet.