1 more tang...too many fish?

[Aquattro]

naesco, I've had this fish about 4 months now. Previous to that it was in the LFS for about 2.5 months. They had a really high price on it, so it didn't get sold. I watched it get fatter as time went on and thought it was a good choice. Since it was different than the last one I had, I thought this was the species that did well. The LFS confirmed this (doh!).
So now I have a tang swimming in circles. It eats like a pig, shows growth and does still graze around the tank, but the last 2 weeks has been mostly circles.
I've ordered a Tunze stream and hope that increases the current and O2 in the tank. There is still a fair amount of swimming room. The fish have full access behind the rocks. I had a trigger that did the loops for a while, and then stopped. I'm hoping this guy does the same.
Since I have the largest tank amongst the people I know in Victoria, finding a bigger home isn't an option.
I'll have to make a decision after the Tunze pump...hopefully it helps.