That is not my friend! If the window wasn't there, it would attack my face immediately. It's like an angry little dog, and has been for at least 7 years now. I don't know why it has to be that angry... Not sure if it get's to move in to the new large reef tank. But perhaps it might keep the smaller fish schooling by chasing them all the timeI spy your little friend peeking out there, hah hah.
It's a Neoglyphidodon melas, or something similar. It has changed colours a bit during the years. Not a fish I recommend for tanks under 100 000 litre if you like to have other fish too