I have an angel fish that I presume either has a bacterial infection or some sort of bladder issue. It started a few days ago when the fish would swim nose down, then turn almost a summer salt. I didn't think much of it at the time. Fast forward a couple days later, the fish would swim down, stop its fins, and the back end would float to the top and the fish would turn over and swim to put the nose back down. Now today, the fish can only float at the top of the water. What do you think?