Ok I'kk jump in on this one as well
I have had at least 4 fish die in the last 5 weeks or so of unknown cause. The fish all should have had years left of their life, 2 have shown what could be missing scales and all 4 got lethargic and breathe heavy before dying within 24-48h.
Never brought a fish from a petstore (have had some from a member on here but none of those fish have died), I'm on different water than you guys...
But I guess that my deaths are linked as they are sort of similar and in the same time frame?