Feeding livebearers. ?

Hi. I have 6 swordtails (4 female, 2 male) in a 30 gallon fish tank with 6 zebra danios and a few apple snails. I usually just feed my fish Tetra Tropical Fish Flakes, but I was looking to start feeding them more nutritious foods. The only problem is that i don't have enough time on my hands to prepare blanched zucchini and other veggies on a regular basis. What else is readily-available, fairly-priced, and nutritious that i can feed to omnivorous swordtails?