Next time you are playing with your trigger, (the fish...not what you are thinking...) try just gently pressing him up against the glass. My old Blue Throat used to just freeze and you could hold him there for 20 seconds or so.
I dug up this old video of my trigger's trick. I bet this response is common to all triggers.
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400 gal reef. Established April, 2007. 3 Sequence Dart, RM12-4 skimmer, 2 x OM4Ways, Yellow Tang, Maroon Clown (pair), Blonde Naso Tang, Vlamingi Tang, Foxface Rabbit, Unicorn Tang, 2 Pakistani Butterflies and a few coral gobies
My Tank:
http://www.canreef.com/vbulletin/showthread.php?t=28436