I have to say that mirror trick works like a charm.
I've been keeping some angels in my sump for the past 3-4 months waiting for the right time to introduce them into the 300g sps tank. The aggressors in the 300g are:
a BIG 6"+ sailfin,
large 5" Powder Blue
4" yellow tang
4" purple tang
This evening I added:
a 6" Majestic angel
5.5" emperor angel
4" regal angel
3" goldflake angel
2" flame angel
At first the tangs went crazy and surrounded the angels into a rockwork. To divert their aggression, I put a big mirror in one corner and the tangs went crazy at their reflection.
Then the mirror fell and I had glass all over the ground.

#@&% me
I put up another mirror (with more support) and the tangs have been so distracted by their own image that the angels all came out and explored their new home.
2 hours later, the angels are attacking their own images alongside the tangs. Now they are all swimming around like best friends! Frankly i think the tangs are too tired from bashing the glass.
