They will eat anything. You should ask about what food they were raised on and try to get these if initially they don't eat. Once you ge them eating, the will eat everything.
I just added as many type of good flakes I can get and mix them together then use this combination for my clowns. I don't use frozen food for my clowns babies or by brood stock.
In my DT, there are other fish that only eat frozen (Marine Betta, Anthias) I mix frozen Mysis or Ocean Plankton to the food that I feed the tank twice a day. My clowns in the DT does eat some of the frozen, they seem to prefer flakes over frozen food. As they get full, they will spit out frozen, but will eat flakes. In feeding the tank, I dump a bunch of food in front of my MP-60 and it get blow all over the tank.