I purchased multiple angels over the past 4 months. A flagfin and flame are doing great. I lost two queens a blue face and four passers in that time span. All but the blueface lived less than 12hrs. The bf made it 8 days. I have checked my water and taken it to 2 of my lfs. My amonia, nitrite was zero. My nitrate was 60, which is common for me. My tank is a 220 with a flagfin, golden puffer, powderblue tang, flame angel, picasso trigger and miniatus grouper. All the fish are under 5 inches other than the puffer and powder blue. I run a SRO 3000ss and have about 200lbs of live rock. My other fish are doing great. So far my lfs have no idea and their only advice is to add a uv sterilizer. The tank has some agression new fish are chased some, but there Is no damage on the dead angels. Any help would be appreciated.