I was doing my nightly check on the tanks before lights out and found my male fryeri upside down, obviously dying. This fish was acting normally 3 hrs before when I fed. The only abnormality I see is a faint red spot on his belly, immediately anterior to his vent. See pic below. I have no idea why he is dying, the only thing I can think of is one of the other males attacked him, but there is no damage elsewhere. I've got him in a qt tank right now, but I'm pretty sure he'll be dead in the next hour. I've never seen a fish go so fast without obvious damage. If it is something other than trauma, something contagious, please let me know what your thoughts are so I can keep any others from dying.