I have a small 10 gallon, pretty heavily planted tank with a pair of guppys, about six week old guppy fry, three otos and a ghost shrimp. About a month ago I added 4 Ramshorn snails. They were doing great, moving all over the tank, laying eggs, just generally seemed healthy. Then last week they all just disappeared. I found one empy shell, I can't see any others. Other than a small 20% water change I did, nothing had changed. The guppy fry and other fish are fine, as is the ghost shrimp. Any ideas? I was really enjoying the Ramshorns. One other thing, the eggs they layed seemed to disappear after a few days or so? Otos eat them?