Well, my suspicions were confirmed. Today I bought a couple more otos to put in the 20 gallon tank with my 1/2 inch A. cacatoides fry. A very small corkscrew snail got into the bag with the fish. While the bag was sitting in the tank, the baby apistos kept tapping at the bag where the snail was at. When I dumped the water out, the snail was hit before it sank an inch. How do they digest the crushed up shells? Bob Dixon