My Betta's been acting weird for about a week and a half now. He's always hanging out at the top of the tank and I've seen him swim sideways a few times - it was only for a couple seconds, but it looked odd.
I think his tankmates have caught on that something's wrong with him, they're starting to pick on him and nip at him. He can't swim fast right now, so I'm worried it's because he's sick and weak.
I tried following a guide for swim bladder disease, so I took him out of the community tank and put him in a separate container - it's a bulbous glass pitcher I use for water changes, filled with room temperature water.
I kept him in there for four days without food, but by the fourth day, he was barely moving and looked really unhappy. I was worried he was going to die. I tried feeding him a frozen pea, but he didn't even notice it - it just sank to the bottom.
I ended up putting him back in the community tank because I was worried about him not moving much. Now he's just sitting in the corner at the top, not moving much, and the smaller fish are still bullying him.
I have another tank that's really calm, so maybe I could put him in there to help him regain his strength. But I'm not sure what to do - quarantining him didn't seem to work, and he didn't eat the peas. He just got really lethargic. The water was still and unfiltered, with no motion, so maybe that was the problem - but the guide I read didn't mention anything about that.