When I used to keep bluegill and pumpkinseeds a few would get it randomly. I'm trying to think what happend leading upto it.Not certain how it happened. He just stopped eating one day and was bloated. Treated him for a month with Epsom salt bathes and he just kept getting worse (I originally thought it was constipation). And eventually he just couldn't keep balance anymore and by the time I realized my mistake and had the proper treatment it was already too late.