My cbs did the same thing to both my mandarin and my sand shifter goby, looked like he was going to body slam them on the rocks. They kept going into the cbs hang out. IMO it was his way of showing his territory. He never picked at them or hurt them (as far as i could see) Now they both spend their day swimming in and around the cbs and he just pays no mind to them. Every once in a while he has to show his strength but has never maimed them. I would just watch like I did for while, just to make sure stranger things have happened.