two of my angelfish have died in the past two days, i noticed something was up cuz there fins look like they had gone thru a paper shredder but couldn't realy diagnose the problem than when i scooped them out i notices spots of missing scales? i've looked online and i can't find anything so anyideas anyone? p.h. is 7.1-7.2 ammonia is 0 can't test the others (outta stuff)