i dont think he be a fishmen as he doent have the skin type or any other chrateristic of one just having sharp teeth doesnt mean he a fishmen and devil fruits make a person not able to swim and they lose their power in water vander decken was a fishmen with a fruit and he was pefectly fine in the water jack wasnt
Wrong on all fronts. It has already been said, but let me emphasis it a bit more.
1) He breaths under water and has a mouth, meaning his teeth and lips, that is highly characteristic for a fishman (no shortage of examples here: Hody Jones, Arlong, Dellinger...). There really aren't many entities that fit those criteria. The fact that hybrids exist in the OPverse, makes this something so plausible to the point the majority of the readers already accept it as truth.
2) We know for a fact that there is an enormous amount of variation in the fishmen gene pool, let alone when you add a human in the mix. Dellinger was a hybrid, yet you couldn't see at all physically he was one and he was able to actually let his teeth and dorsal fin grow out. So your argument about skin type is nonsense and invalid. People are talking about Jack being a half and half, but it's very well possible he's 1/4th fishman or even less. It's easily possible that after so many generations the amount of fishmen genes is so low that appearance and ability wise there's not much to see anymore.
3) DF make people hammers in water, it makes them lose all their strength, which leads to them drowning. Fishmen however can breath under water. Vander Decken was living in a bubble because of this. Seriously. Also Jack was doing pretty fine other than not being able to swim, so you're majorly contradicting yourself here.
first off how that racist it a charater in a manga dont try to mix real life with fantasy dumass and there nothing to rascist about except for his teeth he resembe nothing like a fish man and second the bubble kept him afloat that all it did he was able to brethe underwater because he was a fishmen whose body structure is different thn a human
If he was that fine in the water, he wouldn't need a bubble. This doesn't even make sense what you say.
just the word of a man with no life mixing reality and fantasy and i didnt only say skin i also said charateristic such as the fact that dellinger wasnt a fishman he was half fighting fish kokoko was a mermaid who tail split allowing her to live/pose as a human and you have no proof that jack a fishmen so until proof is shown then he is not a fishmen and you can compare luffy to vander their body is different
Dellinger is a fishman hybrid. This is a fact or did you now seriously believe there was once a drunk human that messed around with a real fighting fish? Even for the OPverse that's ridiculous. Dellinger is a descendant of a fighting fish fishman, just like how Hody Jones is a white shark fishman and Hacchi is an octopus fishman. Despite being part fishman, no one thought he was one till he pulled out his teeth and fin.
We have proof, we have given you proof, which you were completely unable to even remotely invalidate. On top of that it makes perfect sense. Tbh I don't even get why you are so adamant about not wanting to accept this as your denial is rather unsightly and the manner you tried to discredit this strong possibility even more. This really isn't a dubious, highly subjective and baseless matter, but one of those things that's almost so certain that confirmation is only a formality.
And even if you were to disregard almost all proof and common sense, you are still completely unable to explain the reality that if he isn't a fishman, how it is he's actually breathing under water. I think you're just cranky that your own hypothesis got immediately shot down, sank and did drown.