Thank you for the kind words Guy.
Yes a yellow head or pearly jawfish or if you prefer Opistognathus aurifrons
There are three in the tank along with a small foxface, purple firefish and a chalk bass.
The jawfish consist of two males and a female. The males have each had a clutch of eggs in there mouths, hatched and become fish food or pump mush. All three live in their own little caverns.
By the way the tank has been up and operating continuously since January of 2007. It has been through many scapes and hardware changes over the years but the current configuration and fish have been there for quite some time now.