Frank is a muscular goldfish, usually seen hanging out at Goo Lagoon. His name was revealed in the episode, "Slide Whistle Stooges." In "The Fry Cook Games," he is scared and eager to get out of the arena, showing that he has wimpy side and weak constitution. Sometimes he's seen eating at the Krusty Krab such as in "To Love a Patty." He is very buff. His color is an almost a bronze-brown color. And he wears a black speedo swimsuit. In some episodes, he has sort of "squinty" eyes, unlike the ones shown here.
In "Slide Whistle Stooges", Nancy was his girlfriend.
In "Prehibernation Week" and "The Fry Cook Games," Frank had a small, wimpy voice. However, "in Slide Whistle Stooges," he had a big tough voice.
Frank the muscular goldfish is not to be confused with Frank the store owner, the jail guard Frank, and the cameo character Frank.