What else should I add to my tank?

[Palster]

I have a 90 gallon and a sump with approx 90 lbs of live rock under 260 watts of power compact lighting. The tank has been running for approximately 3 months and water parameters are stable. The fish I currently have are:
1 Sunrise Dottyback
1 Maroon Clown
1 Lawnmower Blenny
1 Falco Hawkfish
1 Coral Beauty Angelfish
1 Foxface

I would like to add one more flashy show type fish that is not too aggresive and relatively easy to keep as I am somewhat new to the hobby. I was thinking along the lines of some type of Tang that wont be too big for the 90. Any suggestions would be appreciated.