The Atomic Flounder is a semi-retired supervillain in the Mermaid Man and Barnacle Boy series. He is able to blast enemies with his atomic breath.


In "Mermaid Man and Barnacle Boy II," he is gray, has a green shirt with checkered pants, and a black hat on his head. In his super villain form, he wears a hazmat suit. He appears to be pretty old.

In "The Bad Guy Club for Villains," he has a shark fin, two fish legs, human hands, one eye, an eye stalk on the left side of his head, and has a shark tail. He is shown to be muscular.


"Mermaid Man and Barnacle Boy II"

A cutout of him appears in the Mermaid Man and Barnacle Boy TV show. When SpongeBob is with Mermaid Man and Barnacle Boy, they see the Atomic Flounder who is revealed to be retired. The two joke that he could turn evil again in a snap.

As they laugh SpongeBob (who took the joke seriously) foolishly attacks him on the account that he is a super villain. Seeing this, Mermaid Man and Barnacle tell him to stop as he explained why he attacked the old man. Enraged at this revelation, the Atomic Flounder pushes SpongeBob aside and yells at the two heroes and uses his fire breath to burn Barnacle Boy's head before angrily walking off.

"The Bad Guy Club for Villains"

He, alongside many other villains form a book club even though Mermaid Man and Barnacle Boy think they were up to no good. However, it is revealed at the end that all they did was form a book club.

Missing Man!

After SpongeBob, Barnacle Boy, and Patrick think that Mermaid Man has been kidnapped, they go to Atomic Flounder's home, where they find Man Ray proposing a scheme to rob a bank. While looking for Mermaid Man, SpongeBob cuts through the bank map because he thinks there is a secret pass way behind it, but there is not. The Atomic Flounder tells SpongeBob that Mermaid Man is not there, so the three continue to search elsewhere. Later, at Jumbo Shrimp's house, the Atomic Flounder, Man Ray, and the Dirty Bubble come over. Here, they have a meal and then complain about how SpongeBob, Patrick, and Barnacle Boy have ruined their day. They all agree to get their revenge on the three. Later, they kidnap the three and tie them up to chairs at Jumbo Shrimp's house. Soon, Mermaid Man arrives to give Barnacle Boy a present since it is his birthday, but he also gets tied up. Soon, it is time for the villains to get their revenge. Barnacle Boy has an idea. He asks SpongeBob and Patrick to sing him a birthday song while he plays the harmonica he just gets as a present. They do so and this causes the villains to get annoyed and they kick the heroes out.



Title Role(s) in episode
Season 1
"Mermaid Man and Barnacle Boy II" (tr) Minor
Season 7
"The Bad Guy Club for Villains" (tr) Major


Title Role(s) for game
The Yellow Avenger
SpongeBob Moves In!


  • The Atomic Flounder's atomic breath, which was seen in "Mermaid Man and Barnacle Boy II," is possibly a reference to the Japanese film character Godzilla.
  • He was actually a fish in a lab experiment, but it went haywire and he became the villain he is now.
  • The Atomic Flounder is the only retired villain and the only one who has aged besides Viro Reganto and Jumbo Shrimp.
Mermaid Man and Barnacle Boy (VE)