snails eat dead fish?

Just a quick question. I have an abundance (but not too many) of snails in
my tank; which is ok because they eat the algae and decaying plant leaves.
But do they also eat dead fish? And if so do they consume them fast?

The reason I ask is that I have lost one of my Otto's. I can not find her
anywhere in the tank but she was just there the day before. Could the
snails have eaten her that quickly, do they eat dead fish at all?

Thanks,
Paige