I have had two angels in the same tank for about 9 months (emperor and majestic). So far, they get along better with each other than any other fish in the tank. They spend most of their time following each other around and I don't think they've ever fought. However, I do NOT expect it to stay this way. I am waiting til I have to get a 150 gallon to separate the two of them once they start fighting. The majestic is fully changed, and is about 4 inches long. The emperor has started to change and is about 5 inches long, to give you an approximation on age/size. You can put them together, but definitely be prepared to find one of them a new home at a moments notice if they begin to despise each other.