Fire belly newts question?

I want to put fire belly newts (2) in with my fish.what I have in my tank right now are platys, Cory,tetra,and a little salamander that spends most of his time in the heater.once he gets too big ill move him.but anyway,can I put them in there?I am planning on getting one of those turtle docks that are on the side that have suction cups.and at the most the temp is 78' degrees.also,what do they eat(the newts)