Yellow tangs need a six foot wide tank to live long/avoid stunting. You probably didn't know, but in the better interest of the fish find it another home. If it's still small you have some time before then, but still.
And wow, way to start off with a bang! I personally wouldn't have had a giant wall of rocks, as the water in the crevices is going to be a stagnant, nitrate factory. A valley or whatnot would've been a better choice, but heck, "too much" live rock is better than too little :P
Everything looks open and happy so you seem to be off to a good start, other than the tang.
Got a clean up crew? Lots of blue legged hermits, nassarius, nerites, ceriths and turbos will have you set. Try out some Ricordea florida or yuma in there also, quite interesting and more light loving than other shrooms