i'm guessing this means you haven't been able to either reach in and grab it or scoop it up in a net?
try getting a good-sized net and adding a piece of its fave food inside the net, then after lights out, sit the net near the shrimp and wait...when the shrimp enters the net, scoop it out.
BTW, all CBS get cranky when they get some size on them...we used to have a LARGE (size of my hand) specimen that was always grabbing at passing fish, but we had it so long (a good 8+ years), and it never really did any damage, we simply left it.