Like most newts they do well on live foods which you can culture yourself. Unlike chopped worms or frozen bloodworm they dont die and stink the tank up, with the exception of terrestrial bugs. You have three choices of how to source your live food. Shop bought, convenient but can be expensive, some foods may not be available. Wild caught, free but requires effort, may introduce unwanted pests and parasites. Culture your own, cheap but requires effort, research and space. Aquatic bugs you can culture includes blackworm, gammerus, hog lice, snails (the babies get eaten rather than adults) and daphnia. Terrestrial foods, if you have a terrestrial section they are good but some may be used aquatically. Fruit flies and their maggots, white worm, springtails, crickets, waxworms, pea aphids. A variety of food can be provided for your newts, some of which may establish a permanent self sustaining colony, others will require constant addition. If you check my past threads i have posted about whiteworm, fruitflies in a mantella thread and daphnia.