Over the past few days my big male severum has been hanging out vertically in the upper corner of the tank. I thought maybe it was the rambunctious tankmates finally getting to him (though they've been together for some time, but they are growing and getting feistier). So I moved him to my calmer 125. For the few days he's been there, he's done nothing but sit vertically on the bottom, with the only movement being fins, and mainly only pectoral. He hasn't eaten over this period. Today I come home to find what looks like fungus on the edges of his fins, with one pelvic being pretty bad. What am I dealing with? It seems as though what appears to be fungus (whether it is or not) is only a secondary issue, but I have no idea what to make of it. No meds have been used to now, as I thought he was only stressed in the beginning. I've been leaning toward swim bladder, but I need some more input. I don't want to lose this guy, but I don't want him to slowly suffer either.