It has long been known about the mirror trick for helping reduce aggression, but I was wondering how it would work to take a fish you might be interested in adding to your tank and placing a video of one right next to your tank to see how your established fish respond. For the experiment I used my established Coral Beauty Dwarf Angel (been in the tank for just over a year) and a video of a Flame Angel. Unfortunately it doesn't tell us how the Flame Angel would respond but it does give one an idea of how the established fish would respond without having to go purchase the fish first. Here was the result, for those who are interested: