I agree with everyone else, they go where they want. My first one travelled the tank for a week before staying put, it has not moved in a year besides when it goes into the rock work to split. I feed mine chopped pieces of squid (from the chinese market) for the larger ones, and small pieces of squid and mysis to the smaller ones. I used to feed silversides but it is cheaper to feed mysis and fresh squid.
Good luck and enjoy!