I think Andrew might be biting his tail, but I'm not sure. I do know that half of it is gone, though. I was reading a little about tail biting, and I understand that some bettas bite their tails when they don't get enough attention. I admit that I haven't been giving him as much attention as I'd like to lately, because I've had a hectic schedule and just got back to town after being gone for two days. I'm just not sure if that's what it is, or if it's something else that is causing his tail to slowly disappear. He seems to be very social, so I can buy into believing that he's lonely and bored and wants more attention (he's always so excited to see me or anyone else in my room). So, how do I know for sure that he's biting his tail, and how do I go about fixing it? Right now, he's in a 5 gallon tank. I last changed his water 50% on Thursday, 04 March (it's been a while, I know, but I'm planning on changing it again this weekend, 100% this time). He seemed happy before, when I had lots of time to stare at him and watch him play. His tail didn't start to disappear until I was suddenly busy and not home as often as I was before.
Edit: I also just noticed something else. I was about to go to bed, and I turned the light off (but left Andrew's tank light on, as he seems to be happier with it on sometimes). When I went to turn the tank light off, I noticed that Andrew was kind of freaking out, swimming around with his fins all flared out and whatnot. But the strange thing about it was that only half of his face fins (sorry, I'm not familiar with the technical terms for the different fins) were flared out. He puffed his face out, and only half of the fins from underneath flared out. Is that normal? I've never seen that before. Also, he started freaking out and flipping back and forth when he swam near the filter. He stopped doing all that as soon as I turned my bedroom light back on, so maybe he was freaking out at a reflection on the glass of himself? Wierd. Anyone know what's going on, or have any advice for me?