A Giant Fish Balloon Monster (vocal effects and evil laugh provided by Kevin Michael Richardson) had just appeared in the episode "Uh Oh Dynamo" When the evil giant fish balloon monster appears from under the water he tried to ruin all the people of Townsville's fun and games the girls tried to stop but he's too strong. And he goes on a rampage by destroying Townsville. But the girls used the Dynamo to stop the evil giant fish balloon before he got defeated by a pop by those sharpy things like sparkled wheels from a bowling alley building.
The Giant Fish Balloon is a giant orange, sea monster like creature. He has seven eyes and giant fangs. He is also covered in giant spikes that go all down his back and tail.
- In the episode "The City of Frownsville", The Giant Fish Balloon was seen crying. Later in the show, he was seen laughing when Lou Gubrious slipped on a banana peel. The Girls however, never fight him in the episode.
- Although he is not a main villain, he was treated like a main villain in the episode The Powerpuff Girls Rule! where he was featured along with the rest of the main villains, trying to get the key to the city.
- His physical appearance slightly changed in the episode "The City of Frownsville." In this appearance, he was shown to have yellow eyes instead of white, his fins were brown instead of orange, and his spikes were a dark shade of orange instead of the usual white.
- A claymation version of him was featured in the music video for Signal in the Sky.
- In Demashita! Powerpuff Girls Z, he makes a short cameo appearance along with the original Powerpuff in the final episode.
- It is possible that he is an entire species as seen in Uh-Oh, Dynamo where a tiny Fishballoon creature summoned the Giant Fishballoon from the water to attack The Powerpuff Girls.
- Although it may be possible that these are the only two fishballoons that exist.