I dont wanna be the bad guy here and don't get me wrong thats a beautiful tank, but your pretty much about maxed out on fish right now, I wouldnt add anything else to your tank, maybe one more fish absolute maximum.
The more live rock you add to the dt the less room you have for fish to swim and explore this is especially true with base rock that has no pores and caves for fish to travel through which is what you have, dont get me wrong, the more live rock the better for overall tank stability and health but with smaller tanks there is a fine line.