Platies will eat anything. They are amongst the easiest fish to keep. Like your other fish, platies need high quality flake food (omega one, tetra is ok) and benefit from frozen foods every once in a while. They love vegies so u can put boiled zuchini, peas, or green beans in sometimes and remove the excess. If u have otos, siamese algae eaters, or plecos, or other livebearers they will love the vegies too. Spirilina flakes are good food for plaies along with the regular flakes. I like tetra spirilina.