Welcome to RB !!
I'd advise against it as its wrong to the health of your fish... There was a topic about this yesterday of Reef Central and the general population there advises "NO GO"...
I wanted to know why myself, so I took a hand held mirror to my tank, I literally never seen my clown swim so fast and wedge its-self into a rock to hide, my flame hawkfish however didnt seem so scared, yet it made multiple attemtps to "destroy" its own image in the mirror...
I dont think it would be kind to your fish...
