I feed it nutra-kol Micro feed - Formulated specifically for culturing live foods and feeding herbivorous filter feeders in reef and other marine systems. NutraPlus Micro Feed contains pure Dunaliella salina and Nannochloropsis oculata algae with no additives. Contains high natural levels of carotenes, minerals, vitamins, and fatty acids. (the description)
I also feed it liquid selcon. I feed it about 2-3 times a week.