Never had a snowflake, but had a zebra for a while. They hunt more by smell then sight, and can be tricky to feed in the beginning. Work on feeding in the same spot, they will learn to go there when it is feeding time.
I have had one for a few months just went to the local saveMart Bought a Pound of the silver dollar sized shrimp and feed 1-1.5 every few days or when he comes out of his rock work looking for food. I just cut each shrimp up Into 4-5 small pices and feed with a Fork... mine likes the hunt so he will chase the food on it then thrash about before swallowing it. then be right back for more. I will feed the left over pieces to the Brittle star and my condi just for Giggles my kids lve watching me feed the eel.