Serious .. they sleep between the rocks, with eyes open ... if you were lucky to go down with a spear gun in the winter nights and look between the rocks, you will find it sleeping there, just aim your light and it would freeze and then .. it is done.

Also the fish mouth, the fish lips [if it has some] when the hook hit this area when you catch the fish, the fish can't feel anything because it has no nerves in there. Some of the fish use it's mouth to crack sea shells and stuff like that, so that is why it does not have nerves there. It would be paining like hell if it would feel the pain every time it hits the shell with the rocks using its mouth trying to crack it :)