yeah just cut them through the mouth.. as long as it has a piece of the mouth itll grow. I fragged a 4 inch one into 8 and sold them.
Once you frag them, your going to want to put the pieces in a plastic cup with LR rubble and some sort of mesh on the top of it so they can have soem time to repair and attach to the rock, or else there just going to float around and die eventually.