Since our snail died we decided to try an Oto. Got two. First one died the first night, found him belly up the next morning. And now this morning our second one is completely gone... vanished. We have 2 platys, a Dalmation molly and 4 neon tetras... I'm guessing one of them ate the oto? But which one? We were told that the oto would be fine with the other fish we have.