He may show a different attitude once he settles in, but remember that this is a cichlid. They can snap at any time. I've had fish act fine toward their tankmates for a year, then turn on them and beat them up. Never assume that if a fish acts a certain way for X amount of time that it'll always act that way.
My guess is that when this RD gets comfortable or maybe a bit larger it's going to figure out how to make a target out of your silver dollars.
My guess is that when this RD gets comfortable or maybe a bit larger it's going to figure out how to make a target out of your silver dollars.