Royal Gramma aggressive or territorial?

Good afternoon. I picked up a green chromis this afternoon to add to my tank. I have had a royal gramma and a yellow watchman goby in there for a month. After I added the chromis, he ran, and hide. I was expecting that so I walked away. I came back about ten minutes later and my gramma is coming at the chromis with his mouth wide open and severely harassing my chromis. Is this territorial aggression or just pure aggression?

 

Peachy. I'm kinda worried for when I want to introduce clowns and if they will be attacked as much

 

So I'll need to do a rescape. No bueno...