actually, i meant Eric (Cwebbhokie)...but the same question applied to you too.
i just got this mantis a couple of weeks ago. he was living in a ~2g pico cube tank on the desk at Atlantis in Richmond for about the past 2 years after they found him in one of their big show tanks.
apparently he was eating small snails and hitch hiker blue eyed acro crabs....but i havent seen him touch anything like that yet.
he's slapped around 2 big bad crabs i put in there, and an urchin, but only when they got close to his cave.
he has been eating frozen mysis......but to my amazement he is also taking flake food i give to the clown fish in there which is VERY rare IMO for a mantis to take flake food.
so far, he is the coolest mantis i've ever owned. he comes out and looks at me time to time if i sit down in front of the tank. and he'll come out and chase around flake food. every other mantis i've owned i virtually never saw other than their eyes sticking out of the cave.
if i ever have to take a break from the hobby (coral keeping), i will definitely set up a 20g tank with a big ole' peacock mantis in it and a single fish. that would be fun to keep. theres lots of sweet youtube videos of big peacock's in their own tanks.