I have one and they are awesome little fish! Mind spends his day swimming up and down in the current of bubbles(I do have places in my tank where there are no bubbles). Everyone likes to watch. I haven't noticed him being aggressive toward any of my other fish he usually just does his own thing. That may just be the personality of mine. One warning! Be very careful when netting these fish the have little barbs on their fins that can easily get caught in the net! I found that out the hard way.
That is what I figured. I am trying to figure out which by process of elimination. I took the Angel out today, and if none disappear I can be pretty sure she was the culprit.