there is a possibility that once you add the rock beauty he may fight with the coral beauty,
another thing you may want to know the rock beauty loves to snack on about all soft coral,
he also may snack on snails and hermits , cleaner shrimp can be a easy lunch .
they are also considered not reef safe, beautiful fish but will destroy a reef , you can get by with one that is a juvenile that is under 3 inch ,
once they hit the 3 inch range there demeanor will start to change ,
getting more aggressive along with aiming his attention on corals and rearranging rocks and picking on tank mates.
the rock beauty I had was a nice fish at the start , once he started getting big he changed from model citizen to a holly terror ,
I thought my clowns were bad moving rocks till my rock beauty made them look like angels ,
rock beauty's can move some fairly big rocks that can break glass so caution needs to be taken to keep bigger rocks towards the bottom ,
I finally traded him in for three basslets for my predator tank ,
they also require a tank of at-least 100g+
before you buy any fish it is best to do research first that way you know there habits and demeanor .