Lost another one

Today I found the mostly consumed remains of one of my albino cory cats.  I'm not sure what killed him, there was no ammonia reading in the tank, though I forgot to check the other levels before I did a water change.  In any event, the baby snails in the tank are starting to become a real problem - they're getting big enough to clearly see what color their shells are, especially the ones that were feeding off the dead fish before I removed him from the tank.  Perhaps it is the competition for food that lost me a cory cat?  I ordered a couple of assassin snails online today, assuming they arrive ok, I shall put one in the tank and see if it takes care of the over-population