I have 2 . I got them from someone that had them both together for a long time. But the bigger of the 2 is super territorial and is a prick to the smaller one. I just added an onyx and he's Also being a douche to him.
I just saw a pair of that too at my lfs yesterday and he said it's a bicolor damsel. Every damsel has its aggressive behavior, just saying 2 cents to it. I hope it helps getting an id on this fish.