Earlier this year we started up a 10 gallon planted tank and added our Betta fish. Our Betta seemed like he had a mellow personality, so a few months later we added a mystery snail to the tank. They seemed to be co existing peacefully, then a few days ago I noticed our snail wasn't moving around like it usually does. After closer inspection, I noticed that our Betta had nipped off her eyes and antennae! I thought she was dead but noticed she pulled her trap in a little when I picked her up so I put her in a big glass fish bowl. She started moving around and eating and now her eyes and antennae are both growing back. Sorry for the long story, my question is how big of a space does a mystery snail need? A friend gave us a 2 gallon tank and she's in there right now. I saw a small filter designed for tanks 3 gallons or less at the store. If I got a filter, could she live comfortably in the 2 gallon or does she need a bigger tank?