well feeder fish are always good, but shrimp, beefheart, krill, and flakefood are all good. Make sure they have a varied diet so that they grow properly. I mean I love steak, but I couldnt eat it 24/7!!!
When my p's were small i fed them beef heart and baby food (mixed in blender) it forms this nice creamy stuff
and i got one of thoose wooden sticks (think u use them for shish kabobs?) and stuck a small clump of it on the stick and stuck it in the ground, i did the stick idea cause they see it easier and its more conveinient for them to eat, plus the added baby food gives them nutrients to grow like weeds!