So I divided my 5G tank into 2 sections. Louie started biting his tail, so I took him out to put him into a hospital tank so let his tail heal. I added him back today, checked the divider, and everything seemed to be fine. Louie flared, like he always did, and I left. 10 minutes later, I started to get a bad feeling. I sprinted upstairs, and I about died. I saw Louie on Euphie's side, and Euphie, sitting on the bottom, listless, tail torn to absolute shreds. I threw (literally) the tank top off and got Louie over to his side, grabbed a cup, and scooped Euphie out. Of course this is when I satrt bawling hysterically, feeling like such a crappy owner. He's my first betta fish and I though he was dead. He moved a little, and I was so relived. I ended up putting Louie in a smaller tank and putting him in my sister's room (I don't want to look at him for a little, he infuriated me, even though it's not his fault that he fought) and I put Euphie back in his 5 G with no divider and some aquarium salt. I feel like such a crappy owner, even though Euphie's doing okay, ad he wasn't killed, and he's swimming normally-ish, and is going up to the surface to breath, yadda-yadda. I Think I'll end up putting Louie in his own set-up, made out of a big glass jar from Wal-Mart or something, since he's actually very agressive. I hope Euphie will forgive me, since he was this sweet fish who barely batted an eye, and only flared once when I put Louie in the divided tank. I was just teaching him how to jump for food and everything too. Oh, I feel SO mad at myself. I'm hoping Euphie doesn't become this scared fish, too nervous to come say hello to me or anything. Has this happened to anyone, and did their fish turn out to go close to back to normal?