I had one in a small paludarium once (a long time ago). kinda interesting critter. usually fed it pellets, can't remember if they were specifically for newts, or if they happened to be cichlid, turtle, or some generic pellet it took a liking too. A friend of mine used to hand feed it, by sticking some pellets on her wet finger and putting it in front of the newt. bit her (and hung on) a few times, but I guess it didn't hurt, cause she didn't stop feeding it.
didn't make the newt look terribly bright though...
I've heard the toxins in their skin (most amphibians have this) can bother other critters in the tank, but I think I just kept mine with some feeder guppies.
seemed to be pretty easy to care for from what I remember.