I also just read your other thread. How much Live Rock do you have (in pounds)?
Was it fully cured? Did you get it at the local fish store or online?
How long was the rock out of water before you put it in the tank?
I tend to agree that the tang is exhibiting signs of stress. I'm not sure that your tank is cycled. The cirlce ammonia indicator is not fast enough or accurate enouhg to to be used. You should get an ammonia test kit and use it daily.
If you can tell that the belly is sunken you should take the fish back to the lfs
for now till your tank is ready.