i was gonna mention something about iodine but chrispy beat me to it. i think i remember adding supplements to my tank in *the early days* but soon learned that with regular maintenance, the supplements were not needed.
as for feedings, just as everyone has pointed out, they will eat just about anything - those scavengers!
but i think one of the neatest experiences is when you can feed them from your hand. watch out though... they pinch!