I bought two small snails and added them to my tank and now they are gone. They were never very active in fact I never saw one of them come out of its shell but they both had a snail in it when I added them to my tank. Did something eat them? I have 2 juli cory cats, one Aeneus cory cat, 1 pleco of some kind (my husband bought it so who knows what kind it is), and a small albino clawed frog (about 1 inch or so big). I know a frog will eat small fish when its bigger could it have eaten the snails?