One-Punch Man Wiki

Mad Doctor Fish (マッドドクターフィッシュ, Maddo Dokutā Fisshu) were Mysterious Beings and part of the Monster Association. They lived in a sort of symbiotic relationship with Evil Natural Water, but were killed via oil poisoning.[1] As of the revision of Chapter 114 into Chapter 110, the Mad Doctor Fish are no longer explicitly identified by name or disaster level.


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 up to six eyes, though the number varies per fish.


Human Monster Saga[]

Monster Association Arc[]

As a last resort, Master Joe opens the tank holding Evil Natural Water, releasing it as well as the fishes to attack Atomic Samurai's disciples and Tongara. The fish devour Master Joe, and Evil Natural Water uses them to attack the humans as it rampages down the hallway. Once Tongara is lethally wounded and forced to stay behind, his body and battle suit are torn to shreds by the Mad Doctor Fish.[2]

More Mad Doctor Fish appear when Evil Natural Water attacks Child Emperor, again launching them at its target. They chew up some of Child Emperor's backpack's arms and weapons, but he manages to dispose of most of them.[3] Once Child Emperor freezes Evil Natural Water, it absorbs the oil from Sludge Jellyfish's body to reduce its freezing point; this poisons and kills all the Mad Doctor Fish in the process, and their corpses are expelled.[4]

Abilities and Powers[]

Mad Doctor Fish devour a monster in mere seconds.

Because their collective threat level is Tiger, it can be inferred that the Mad Doctor Fish are dangerous, but not extremely powerful. They act as an effective means for Evil Natural Water to conduct a variety of long-ranged attacks.

Physical Abilities[]

Powerful Bite: Mad Doctor Fish have a strong bite that can easily pierce the flesh of other mysterious beings. They are able to completely devour weaker and wounded opponents in seconds, and even tear apart Tongara's highly durable armor. Mad Doctor Fish could also chew through Child Emperor's metal weapons to break them.


Participants Chapter(s) Episode(s) Result
Evil Natural Water and Mad Doctor Fish vs. Atomic Samurai's disciples and Tongara 110 None Win
Evil Natural Water and Mad Doctor Fish vs. Child Emperor 121 None Loss


  • The Mad Doctor Fish are the only monsters in the series so far to live in symbiosis with another.


  1. One-Punch Man Manga; Chapter 121, page 16
  2. One-Punch Man Manga; Chapter 110
  3. One-Punch Man Manga; Chapter 121
  4. One-Punch Man Manga; Chapter 122


Monster Association
Executives Black Sperm *Evil Natural Water *Homeless Emperor Fuhrer Ugly Gums Overgrown RoverNyan Elder Centipede Gouketsu 
Demon Awakened Cockroach Baquma Bug God Building Booper Devil Long Hair Do-S *Eyesight G5 Hundred-Eyes Octopus Vampire (Pureblood) Rafflesidon Royal Ripper Face Ripper Fist Fight Djinn Free Hugger Rhino Wrestler The Three Crows Senior Centipede Showerhead Super Mouse Unihorn The Great Food Tub 
Unknown Gyoffrey Goddess Glasses Venus Mantrap Junior Centipede Haragiri Rosie Choze Benpatsu *Hamukichi *Volten *Evil Eye Gale Hellfire Evil Eggs ManakoPlatinum Sperm Sword Devil Executioner Raptora *Reptera
Mysterious Beings
Dragon (or higher) Boros Orochi *
Demon 170,000-Year-Old Cicada Larva 170,000-Year-Old Cicada Adult Armored GorillaAwakened Cockroach Baquma Beast King Bruinado Bug God Building Booper Deep Sea King Demonic Fan Devil Long Hair *Do-S *Eyesight Face Ripper Fist Fight Djinn Free Hugger G4 G5 Game-Berus Giant Crow Grizzly Nyah Hundred-Eyes Octopus Jumping Spider Macho Daikon Mosquito Girl Rafflesidon Rhino Wrestler Royal Ripper Scaledon Senior Centipede Showerhead Sky King Subterranean King Super Mouse Surprise-Attack Plum The Great Food Tub The Three Crows Unihorn Vampire (Pureblood) 
Wolf Himawari Hotdog Messenger of the Seafolk Piggy Bancon Tongue Stretcher
Less than Wolf
Unknown Alien Seer *Ancient King Angry Grandpa Autumn Phantom Red Golden-ringed Dragonfly *Benpatsu *Choze DarkDark Matter Gunner Eagle Enamel Evil Eggs Evil Eye Evil Natural Water *Falcon Fish of DarknessGale Giant Salamander Gigakigan Goddess Glasses Gyoffrey Hamukichi *Haragiri Hawk Hellfire Junior Centipede Kite Lord Great White ManakoMen's Esthetician Man *Platinum Sperm Rosie Raptora *RepteraSage Centipede Suppon Sword Devil Executioner Venus Mantrap Volten *