My neighbour's basement dwelling son keeps claiming this is a possibility, but. He's just never going to meet a woman who looks like Super Mario.
I think when a fish dies suddenly, we have to try to figure out why. You look at the body. Nothing shows? Then you check the water, the conditions, your set up, your routines. If nothing jumps out, then it's just what happens. You make an effort to understand, but we aren't much more equipped than than doctors were in the pre-scientific era. We look at the situation and make our best guess. We can't see inside the fish, where it all happens.