I have tried to keep a Flame Angel in my tank twice and both times the fish died after a couple of months for reasons I cannot determine. In both cases, I planned for the Flame Angel to be the last fish added since they are supposed to be more aggressive than the other inhabitants. I have a 125 gal FOWLR set-up with a Fluval canister filter and plenty of power heads for circulation. My water parameters are always perfect except for Nitrates of 20 and I change 30 gal new SW every 2 weeks at which time I also clean the filter. The other inhabitants are 2 Heniochus Butterfies, 1 Klienii Butterfly, 2 Ocellaris Clownfish, 1 Yellow Tang and 1 Blue Reef Chromis. The 3 butterflies have been in the tank about 1 1/2 years and have grown a lot and are very voracious eaters. The Tang is smaller and somewhat timid, but is healthy.The Clowns are just playful. In both cases, I had the Flame Angel in QT for over a month including 3 full weeks hyposalinity which they seemed to tolerate well. After transferring to the DT, the first Flame lasted a couple of months and the second only lasted about 3 weeks. The first Flame had a color change (more Orange than Red) right before it died, but the second had perfect red and black color when it died suddenly. Although I did not see any evidence of abuse by other fish, the 3 butterflies are all 2-3 times larger than the Flame Angels, so I'm wondering if they might have been harassed to death. I never saw them being chased, but the Flames seemed to stay away from the butterflies and were definitely reluctant to join the frenzy at feeding time. Agelfish are supposede to be a bit aggressive, but I never saw that with mine. Is it possible that the Flame Angel is just too small to be kept with larger butterflies? Any thoughts on what happened?