The Caped Cod is a demented homicidal cod who proclaims himself as ruler of the sea. Delusionally, he believes garbage items are his royal subjects. He first appeared in The Dog Who Cried Fish.
When he first saw Dudley, The Caped Cod got paranoid and thought that he was the king of land because of the toy crown he was wearing. Suspicious, he battled him for his "kingdom" and lost, then tried to flood the city but got captured in the end. Jailed in a clam at the Petropolis Aquarium for the criminally insane, he vowed revenge on Dudley.
In Cold Fish, The Caped Cod escaped and tried to flood Petropolis again in order to make it part of his kingdom by melting the Riceberg Ice Bird Iceberg, in which he now has a sidekick named the Seal of Approval. He also did this to get revenge on Bryce Riceberg because she didn't invite him to her wedding and they were best friends in middle school. The Caped Cod was once again defeated in the end.
In Hush Puppy, The Caped Cod, along with the Seal of Approval, again tries to flood Petropolis while enclosing the whole town with a glass dome. But thanks to Dudley's constant yelling, the dome shatters, letting the water out, and The Caped Cod is once again defeated by imprisoning him in the fish bowl.
In Cod Squad, he returns for more vengeance and time he recruits two henchmen, Lofty Perch and Puffer Fish. He uses a giant mechanical shark in which he calls him "Myron" and uses him the swallow all of the fisherman at the Annual Petropolis Fishing Tournament and places the bomb inside "Myron" and starts detonating. But with Dudley's help by using one of Keswick's fishing gadgets, he hooks onto the bomb and lures it into the water. When The Caped Cod notices that the bomb is about to go off, it explodes send him into the air, falling into the fish bowl and is once again arrested by Dudley and Kitty.