I have 2 mini gbta's. the one the clownfish hosts is little bigger than golfball size, is fed by me or the clown, is out in the open and never bubbles. The other one is small, more like a robin's egg in size, is hanging out underneath a montipora cap, is never spot fed, and is bubbled 24/7. Both, I would say are happy as they have never tried to move on me.