Hyooman tribe

The Hyoomen Tribe (also referred by Jake as Fish People) first appears in "Susan Strong." They are a primitive race of mutant humanoids who, like Finn, wear uniquely animal-themed hats. They are rather paranoid and speak in strange verses. After Susan discovers the Candy Kingdom, they threaten to eat the entire kingdom and all of its inhabitants (Except "Red Stripe Man," AKA Peppermint Butler) because Susan discovered candy was delicious. Nearly all Hyoomens have what appear to be gills and fins on their heads, revealing that the Hyoomens are not human, but in fact mutants, a realization that greatly disappoints Finn. In the original storyboard, the hatch to the Hyoomens' home has "Biohazard Danger" printed on it, although this does not appear in the final cut of the episode. Unlike the rest of the Hyoomen Tribe, Susan does not remove her hat at the end of the story; the possibility of her being human remained in the air.

Although the Hyoomens tried to eat the Candy People, when Finn encounters them again in "Beautopia" he insists that they deserve to be helped as much as anyone else because they are just misguided. Jake on the other hand insists that they were just creepy "fish people" and didn't know if they could still be trusted. Nonetheless, the duo helps to save them from the Lub Glubs. As Susan Strong explains, long ago the Hyoomen Tribe lived in a mysterious fallout shelter-like habitat located deeper within the underground sewer complex, which they call "Beautopia." Finn and Jake helped drive out the Lub Glubs with fire (which the Hyoomens are also terrified of), and they moved out of the garbage heaps and back into their old buildings.

Appearance
Hyoomens range from very short to tall and appear anatomically identical to humans, other than their fish-like heads, which feature scales, fins, and sometimes gills which could be caused by the nuclear fallout that irradiated the land that is now Ooo.They dress in primitive garments and accessories. Each member of the Hyoomen Tribe wears an animal hat, which hides the distinctly non-human features of their heads.

Trivia

 * Finn teaches the Hyoomens various words when he still thinks they are human, and so they become known as Hyoomen after the way they mispronounce "human."
 * The animal hats on the Hyoomens' heads at first identify them with Finn, who also wears an animal hat; however, the hats ultimately prove to have been foreshadowing the Hyoomens' false appearances.
 * Adam Muto states that Hyoomen are not as frightening as Candy Zombies, which is why the Candy People did not explode.
 * Though Celina, one of the Hyoomens, is shown to have bangs when she takes of her panda hat she has no hair.