Great fish! IME they will only harass or be harassed by other blennies or fish that look really similiar in coloring. In my old tank the royal gramma and the bi color used to knock heads when they got together during feeding. The rest of the time they stayed at opposite sides of my 150g. I guess the black/burnt orange and purple/yellow where close enough in color for them to dislike each other. Mine never chased the firefish, but to be honest I have never had a firefish last more than a couple of weeks. They are just too skitish in big tank IMO.