Flame Angelfish are very susceptible to Brooklynella and Amyloodinium infections (maybe your flame has Brook?). They are also very easily affected by water quality...if water quality degrades, you will first notice them having difficulty breathing and having a hard time closing their gill covers. Another common illness for angelfish is Lymphocystis - clumps of lumpy white or gray matter at the base of the fins.

Is there any way you can post a pic Ross?

W.