User blog comment:Woohoot/The potential of Fishmen/@comment-3203286-20150708151125

You've set out several theories quite well.

The main issue I have with fishmen is that it's explained that they're so much stronger so they can survive at the bottom of the sea. Now, the pressures at the bottom of the sea at say, 5000 metres deep, is in the thousands of tons per square inch range. Unless a fishman is literally thousands, if not millions, as times as dense as a human, they would be crushed in a fraction of a second. If the water is only dense enough that at the bottom of the sea you only need to be 10 times stronger than a human, that water is less dense than most gases.