sorry to hear your loss, but both of my BTA's have never moved from where I put them. To prevent this, I made sure all my water parameters were perfect(what are yours?) before i introduced them into my tank, and i guess I was a little lucky also. Ammonia=0ppm nitrites=0ppm nritrites=0ppm, etc. Mine just shrink when the lights go out. Also. having a small clownfish helps with acclimation too.