I have a figure 8 puffer... A couple days ago, I noticed that he wasn't using his left fin sometimes and was slowly bumping into things. Today he's been vertical with his tail pointing straight up. At one point he was even resting his tail against an object just to keep it down. Now he's mostly swimming in a normal position, but rarely using his side fins (Although he does use his small tail fins.) and still goes vertical from time to time and spends all his time at the top of the water... I woke up tonight to check on him and found him sucked against the water filter and figured he was dead. I went to get the net and when I came back, he was swimming around again with the same problems. And it's hard to tell, but he may be getting a slight film over his eyes... Even as I'm typing this, I feel so bad because he keeps coming over to look at me like he's asking for help. (I know, I know) I've called multiple pet stores and no one seems to have an idea.
The tank is just over a month old. It's freshwater, but I have salt added. Ammonia levels are a bit high. (And I know that's not good.) Temp is 75. He's fed bloodworms, but stopped eating so much a couple days ago. I was feeding the whole cube each day. No change in his coloration since I bought him.
Any help is appreciated. I'll check back in the morning.