About three months ago we started a 16 gallon tank with two damsels (different species). The more aggressive of the two who we’ve named cocoa occasionally chases the other damsel out of the bottom of the tank but does not do much else. The topic of concern occurred when we got our first coral (Duncan). Cocoa will occasionally check out the new coral and bump into it. When he does this the coral closes up and because cocoa does it so frequently it hardly ever opens. Is this an issue, if so how can I fix it without removing cocoa?