Taken from:
http://www.chucksaddiction.com/cleanupcrew.html
FISH - I know of only one species of fish that can be considered truly beneficial, and by that I mean it performs such a good service that its contribution in keeping the majority of algae species in check far outweighs its contribution to dissolved nutrient levels. Zebrasoma scopas - The brown scopas tang, the one fish species that I will always have in any coral display aquarium where algae must be kept under control.
*** I know it is another tang... and I do not know for certain it eats what you want it to eat- but you may want to look into it.***