There are plent of fish in the sea unfortunately for this one he lives in a cylinder and that happy home is just out of reach but ignoring that fact it at least looks like a fish under the sea, right? :)
I'll probably add to this so don't fuss about the weird way the arm fin attaches and small details. I wanna try a grey color for the alphas add in caustics and plants and some other details so it's not final but feel free to borrow and adapt as you wish. So far this has been proof of concent that I can even make 'water' on sketchfab.