I have a small female betta with lots of mollies, swordtails, some corys and they are fine together. However, she does sneak up behind my older molly fry when they are sleeping at night, but as far as I know she hasn't eaten any. I did have a few really tiny fry that she would chase, but the rest of the fish in the tank would too. I think "someone" might have eaten them since I haven't seen them in a few days. But yeah, If my betta died for some reason, I'd definitely get another. She's so cool to watch! She has so much personality. I've always seen bettas in a small bowl just floating there and have never seen a betta in a 30 gallon tank so I was pretty curious how she'd act when I put her in. She's very active and curious. She's definitely one of my favorites.