As much as I know I shouldn't be surprised I still am. This guy was solid. Never spooked by any tank mates. Never spooked by anyone walking past the tank. Always active. Ate anything you put in the tank and always ate a lot. I'm guessing he smashed his head on the glass pretty bad. A few days ago it started. Couldn't swim straight or keep balance. Got worse every day until he finally laid to rest. He went from about 7 inches to 14 inches in 4 months...