Not to detract from the original post but some fish are just picky about their food. I got my purple tang and powder blue at about the same time and they were the tiniest I've seen. Powder blue eats everything and grazes on rocks all day long. Purple will also graze all day long and eat brine shrimp, pellets, flakes, nori PE and virtually everything else I put in the tank but will NOT eat Hikari mysis to this day years later.