i had one in a 200 gal. display. i thought it was lunch when i didn't see it for like 2 months....but one day it pop out of the rocks like a ground hog....lol.
I have had mine for 5 years. He is currently in a 120g. I see him ALL the time. He is always around. Hopefully this behavior continues when I am done my upgrade to a bigger tank. BTW, he is completely reef safe.