I have a betta sorority, and had purchased 2 snails for the tank. 20gal, 3 girls (my fourth was an older betta, and passed a few weeks ago.) The girls were picking on a particular snail, and I moved it to another tank. I prefer purchasing baby bettas, due to the fact that I get to watch them grow, and keep them longer. I recently got a baby a few months back, and have kept it in a 5gal (with the large snail) until it was large enough for the big girl tank. The tank is filtered, planted, and has an airstone bubbler for oxygen. I regularly check my water quality, and have never had an issue with that. Yesterday morning, I saw my once thriving baby betta being eaten by the largest snail. The fish was fine the night before, swam up to eat, everything was normal. I know snails will eat dead or dying animals, so I had assumed something had happened with the fish and the snail did what nature does. Last night, I went to sprinkle in some fish flakes, and an algae tab for the snails, and the large snail was attacking a smaller snail that came in on a plant, wrapping it's body around her shell, similar to what I observed happening to the dead fish. I quickly removed him from the tank, and the small snail returned to eating and moving around normally, so she was not dead or dying. Also, every time the female lays a clutch this larger snails eat it. Why is this happening, and what do I do? I can find no information online.