The bicolor parrotfish (Cetoscarus bicolor) gets 30" long and has an extremely poor survival record in captivity due to the fact that they eat mostly algae from between the polyps of corals. They are pelagic swimmers and most definately not reef safe. They will munch on corals looking for the algae as well as sampling anything else they feel like tasting. They also eat and digest pieces of LR, excreting it as sand - because this is the primary way they wear their teeth down, it is difficult to provide enough material in a closed system to keep the teeth/beak from overgrowing. From what I've seen, they aren't commonly offered at LFS.