More on feeding....
Feeding/Foods/Nutrition: Types, Frequency, Amount, Wastes
Stomach contents analysis of wild specimens shows these fishes to be quite omnivorous, browsing widely on benthic invertebrates (worms, mollusks, fish eggs, sponges...), algae, and more. Getting them to start and accept food in captivity often proves difficult.
My advice is to continue with whatever foodstuffs your supplier was utilizing, expanding offerings to include as much variety of fresh, prepared frozen and dried matter as you can. Soaking food with supplements including vitamins and appetite stimulants is encouraged. Other writers list shrimp species, squid, open shellfish, spinach, prepared sponge-containing products, live rock, and more as suitable foods.