+1 for everything
@Hingis had to say.
They like to be quite high up in your tank, as close to the lights as they can get - and usually very close to your flow pump/wavemaker. I find my quadricolor bta prefers to have significant flow running just over him, but not actually directly on him. When I first brought him home, it took him all of 30 minutes before setting off to find his new spot, and then he moved a few times (Admittedly sometimes with a little help from me to make him hate the position he had chosen), and then finally settled in a perfect spot for me, where he remains 6 months later.
when they settle, they prefer a crevice in the rock. they put their foot right up under a piece of rock, then extend themselves out and live like that. Mine goes through cycles (seems related to meaty feeding) where he deflates and expels all his old waste and zooxanthallae, in order to bring new fresh ones on board. during this time he looks very shrivelled and thin, but is back to himself the next morning and looking as good as ever. I wouldnt be too concerned that he looks small right now - their size can vary greatly, and if he is not settled yet, he may just be staying small to make it easier to walk around to find a new home.
As
@Hingis said, the mouth is a good thing to watch - the moment it gapes open, hes in big trouble. If he hasnt bleached, and the mouth looks tightly closed, then I would say youre good
