Welcome to the forum, ccronje.
And congratulations on your powers of observation! I have a similar group of angels and they always look pretty much the same to me. Any color shifts were attributed to swimming nearer or closer to the lid LED
. I only keep one of the two on. I will be sure to take a closer look! Thanks for your informative post.
This is 2. The other 5 declined to be photographed. Two are black. One is missing half of it's dorsal fin. It came to me that way after being picked on in the previous owner's tank. i wonder if it can regenerate.