Keep them low. Let them spread like Stevo said to other rocks. Then you should cut them with a sharp knife, scissors, scalpel. Cuts will heal faster than ripping them apart. You are dealing with a small tank. Zoos can be a little more toxic than most when cut. If I cut zoos, I always try to remove it before I cut it. Not completely necessary, but it's a good method to keep them from polluting your tank. They grow pretty fast. You should be fragging it within a month or 2.