My natts staple diet is shrimp, occasionally complemented with chicken, fish fillet and smelt. Two or three times a month they get a couple of feeder minnows to hunt down.
My manueli only accepts feeders, so he gets a minnows every few days. I'm trying to make him eat prepared foods as well, so no luck so far: that chicken bastard is actually scared of pieces of shrimp, and hides as soon as I drop a piece in his tank