In chapter 824 of One Piece, Jack is shown lying motionless on the ocean floor, waiting for his crew to come and rescue him after being defeated by Zunisha the giant elephant. His mask is broken and his shark-like teeth (resembling Arlong and Hodi - the shark fishmen) is revealed. However, unlike other devil fruit users, he does not pass out or have any difficulty breathing in the ocean.

My question is: is Jack who happens to be a Zoan type devil fruit user also a fishman, or is there any other possibility as to how he can survive for so long under water?

  • There is no definitve statement yet what Jack is. Like you said, a fishman is a likely possibilty.
    – deviantfan
    May 8, 2016 at 5:12
  • This reminds me of Vander Decken IX from fishman island arc who was also a devil fruit user. Was he ever shown having difficulty breathing in the ocean?
    – Naveen
    May 9, 2016 at 0:54
  • 1
    I don't think so. But why is breathing relevant at all? DFs take to ability to move under water, they don't necessarily suffocate the user. It's just that other species can't breath udner water like fishmen can.
    – deviantfan
    May 9, 2016 at 3:49
  • 1
    @deviantfan That's the point. So if Jack is able to breathe underwater, he is most likely a fishman right? or is there any alternate explanation?
    – Naveen
    May 15, 2016 at 12:49
  • 1
    @Naveen Doesn't Vanderdecken always wear a bubble-suit when he is not in the palace or on his ship?
    – Gravinco
    May 19, 2016 at 13:01

7 Answers 7


Yes, Jack being a fishman is the only logical explanation for him surviving in the middle of the ocean. As you noted already, he looks like a fishman too. His devil fruit prevents him from moving but that won't stop him from breathing (remember in Arlong park, Luffy could breathe while his body was under water when Nojiko (Nami's sister) and Genzo got his head outside of the pool).

It also seems it was not the first time he found himself at the bottom of the sea as he is expecting help as if it was normal, and we can assume he either can speak with nearby fishes or he has a vivre card on him, and is only going to die if nobody comes to his rescue before he dies from hunger.

  • 1
    iirc it wasn't Nami but her sister and the old guy with the pinwheel
    – Darjeeling
    Jul 10, 2017 at 0:11
  • @Darjeeling true!
    – Shautieh
    Jul 10, 2017 at 1:28
  • @Darjeeling when I watched the anime Luffy thought of the old guy when he used the gomu gomu no pinwheel.
    – Callat
    Jul 10, 2017 at 12:56

In direct contradiction to the previous answers. Jack is not described or defined as a fishman according to the one piece wiki linked here Jack Description link

Jack is a man of massive stature, dwarfing his crewmates and even the very large minks Inuarashi and Nekomamushi.

Key phrase being Jack is a man. Given that there is also substantial evidence adding to the credibility that he is in fact human.

Fishmen in appearance

It is further described in the wiki that Fishmen are described as the following:

Fishmen are more fish-like than merfolk, usually looking like a combination between a man and a fish or other aquatic creature, such as an octopus, manta ray, or sawshark; however, they still have legs (in fact, Decken has four). They also have gills between their shoulders and necks, sometimes covered by their clothing, as well as often having webbed hands. Depending on species, they may have multiple limbs (mainly extra arms).

Linked here

Given that all fishmen have some sort of gills between their shoulders and neck and that we have seen Jack full frontal topless and he's shown no signs of these due to the fur coat that he wears.

This can mean 1 of 3 things:

1) He is not a fishman and there is a logical possibility for why being above head level submerged in water wasn't causing him to drown, die or freak out

2) He is a merefolk but it hasn't been fully discussed yet and his lineage and capability.

3) He is actually a fishmen but couldn't move due to restrictions via devil fruit powers.

I disagree with reasons 2 and 3 because what sense would that make? He is the first antagonist in the series to not face any of the straw hats bringing him back either in the current whole cake arc or the next arc (hopefully wano country) ruins that nieche for his character. If he was in fact fishman or merefolk why didn't we see or hear anything about him from the fishman island arc? Or Jinbe? Or Kienmon and momonosuke? It doesnt make logical sense that all of those ppl just conveniently forgot him.

In summation I believe that reason 1 is the fact here. But that leads to the burning question, how is he ok being underwater?

There are 2 possibilities in this case, the first is that as a zoan type he could have matriculated his lungs to a point where they hold more air without expanding the rest of his body due to enhanced control over his zoan power.

The second and most likely case is that he is in fact drowning to death but hes such a tough bada** that he doesn't show that he even cares and might actually survive.

Truth of the matter is

Nobody actually knows for sure beccause it's too soon to tell, we will know for sure once the manga reaches a point where the straw hats or someone deals with Kaido and we learn a bit more about the beast pirates. But as of right now with the information we have in front of us. Jack is a man.

  • 2
    +1 for we don't know. +1 for thoughly thought out. -1 for "Jack is a man". Per appearance, he looks like Dellinger who is a hybrid (and actually has characteristics similar to the unclassified Gekko Moria...huh). Per the quotes, man =/= human and wiki =/= canon and bad writing =/= good evidence. The rest of your arguments are speculation. Your answer would be correct if it were just "We don't actually know"
    – kaine
    Apr 17, 2017 at 20:57
  • @kaine Jack is a man the wiki says so. In order to prove that he is not there needs to be a change in the wiki or some other credible source that says so. At the time when I looked into it. I found nothing. So in my defense I don't believe that I deserve a -1 at all.
    – Callat
    Apr 17, 2017 at 21:33
  • 5
    the wiki isn't credible. It is user editted, noncanon, and not quasi-peer reviewed (by which I refer to how this site works). Answers on this site are required to be more credible than that wiki. You still netted a +1 which is the max I can give you.
    – kaine
    Apr 17, 2017 at 23:03
  • Citing the One Piece wiki is absolute trash. I myself tried to put the info that he's probably a fishman into the wiki, and some asshole edited it out with "no", giving no explanation whatsoever. And to be clear, the wiki doesn't discourage speculation as long as there's clear evidence (though it has to be edited out once disproven). There are plenty of articles that use the exact format I tried to use.
    – codetaku
    Oct 23, 2018 at 13:25
  • I feel like since we now have Wano being explored in the manga we might get some expose on this. If I come across anything further I'll be back to update my answer.
    – Callat
    Oct 24, 2018 at 2:36

Jack is a half breed, like the fighting fish half-breed in Doflamingo's crew. It would explain his human appearance and his teeth changing just like Doflamingo's crew mate, and being a DF user, it restricts his movement in water.


Just an idea, but maybe there is something about the synthetic devil fruits that they all used that decreases their susceptibility towards water?

Or maybe it could be related to Kaido and his inability to die.

There are a lot of unanswered questions that could be tied to why Jack can survive underwater, but I personally don't agree that it's because of being a fishman. The creep from Fishman island that wanted to marry Shirahoshi couldn't survive in water because he had a devil fruit power.


I think he is part fishman. From what I could tell the moment his mask came off he resembled that of a predator-type fishman. I believe he can breath under the water but he is immobile.


Jack is not using a synthetic devil fruit then why wouldn't most of Kaido's crew be using them if you could just make a Ancient Zoan whenever why make modern animals Sapi also looks more human then fish man so Jack could be half for all we know .


Most of you are saying either he is not fishman but human or hes a fishman and not human, maybe even a merman. But how about half? It is shown to be possible that someone can be part fishman and part human. example: Dellinger, He was a human that was part fighting fish so it is possible that Jack is part fishman, explaining his human appearance but seemingly fishman strength and abilities such as breathing under water. He also seems to have horns, but those do have metal parts at the beginning on his head, so it is possible they are fake.

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