snails

Unless the snails is so small that it can fit into their mouth, i would say its quite safe. Plecos are not very efficient algae eaters, some might not even eat it.

Malaysian trumpet snails are the only ones I've found to survive with my cichlids. I haven't tried the japaneese trapdoor snails, but they may have a chance as well. Mystery snails, ramshorns and apples will not last long at all. All of my American cichlids will cruch what fits in their mouths, and anything that doesn't will eventually get yanked out of it's shell. The MTS's survive well, but of all the snails I've tried they are the least effecient with algea.
Dave