1,103 Pages

Mad Doctor Fish (マッドドクターフィッシュ, Maddo Dokutā Fisshu) are Mysterious Beings and part of the Monster Association. They live like parasites within the liquid body of Evil Natural Water.


The Mad Doctor Fish's appearances are based on red garras (also known as doctor fish), but they have larger jaws and sharper teeth that bear a resemblance to carnivorous piranhas. They also appear to possess an unusual six eyes.


Human Monster SagaEdit

Monster Association ArcEdit

The Mad Doctor Fish are seen swimming in the fish tank containing Evil Natural Water. A monster breaks the tank holding Evil Natural Water, releasing it as well as the fishes, to attack Atomic Samurai's DIsciples. They devour the monster that released them, and Evil Natural Water then launches them at Iaian, but he easily slices them up.[1]


Participants Chapter(s) Episode(s) Result
Mad Doctor Fish vs. Iaian 114 None Loss

Abilities and PowersEdit

Mad Doctor Fish Chew

Mad Doctor Fishes devours a monster in mere seconds.

Because their collective threat level is Tiger, it can be implied that the Mad Doctor Fish are not extremely powerful. However, they still act as an effective mean for Evil Natural Water to conduct long-ranged attack.

Physical AbilitiesEdit

Powerful Bite: They have a strong bite, able to easily pierce the flesh of other Mysterious Beings. They are able to completely devour weaker and wounded opponents in seconds.

Trivia Edit

  • They are the only monsters so far live like parasites in the body of a monster.


  1. One-Punch Man Manga; Chapter 114


Community content is available under CC-BY-SA unless otherwise noted.