Bicolor Chromis Just Hanging Out?

[infamous]

I just picked up a few Bicolor Chromis today, acclimated them appropriately, and put them in my tank. Two of them are doing just fine, but the third one is just hanging out in the back of the tank, not seeming to do very well. He seems to just kind of hover for a bit, and then float on his side until he almost gets to the top and then come back down and hover again. He looks physically healthy (although his back fin looks nipped, but I'm not sure that has anything to do with it) and for now I'm assuming he's kinda shy and needs a bit of warming up to the rest of the tank.

I've just never experienced a new addition quite like this before, and just wondering if this is more normal than I am thinking?