Without knowing the size of the tank I would say a solar fairy wrasse, great color and hardy. I have the LFS ordering me one for my 135 FOWLR right now.
is this FOWLR or reef?
I want some chalk basslets myself...later down the road when i get another tank going!
They school and are kinda like sea bass!
Also blue-green chromis or blue reef chromis are awsome for adding some life to a tank!
Well, the yellow tang will out grow your tank in a short time. they really need a 6 ft tank.
you could do pygmy angel, midas blenny, fairy wrasse, bi-color or tail spot blenny - but not knowing what else is in the tank, its hard to suggest anything else.
T