I have a 24 gallon Aquapod with a Royal Gramma, 2 spotted cardinals, a Tailspot Blenny and a Clown Goby.
Here is what goes on.
Sorry video did not load. Here is one shot of him ready to chase cardinal.
Is he chasing relentlessly, or just chasing the cardinal away from his home?
I've only seen them chase for just 6" or so, and then turn around which is just protecting their home, not aggression IMO
Most of the time just charges with mouth open. More on the left side of tank but at times anywhere. It isn't non stop and the fish don't hide they just run away and then go right back to the same place. But once and a while he does seem to hit them.