Humphead Parrotfish / Atuhong
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Humphead Parrotfish / Atuhong
Bolbometopon muricatum
Photo © Robert F. Myers
The atuhong is the largest of all the parrotfishes, reaching a weight of at least 150 pounds (68 kg). Only one other green fish, the tangison or Humphead Wrasse, reaches such a large size. The tangison has a normal, fish-like protruding snout with thick fleshy lips while the atuhong has a vertical head profile and teeth fused into a beak that is not covered by the lips.
Unlike most parrotfishes, adult atuhong of both sexes are similarly colored. They are uniformly dark green with the leading edge of the head light green to pink. The outer surface of the beak is nodular rather than smooth. Young fish, known as pachak, are dull gray to brown with scattered white spots. The characteristic steep forehead begins to develop at a rather small size of about eight inches. Medium sized individuals with a steep head profile are known in Chamoru as påtgon atuhong.
Most parrotfishes feed on the thin film of algae scraped from the outer surface of dead coral or rock. The atuhong is the only parrotfish that feeds substantially on live corals. The crunching sound of the fish biting into the coral can be heard for quite a distance underwater. It is reputed to use its humped forehead to ram corals so they can be broken into more manageable pieces. Atuhong typically travel in groups along upper edges of outer channel or seaward reef slopes, but are extremely wary and difficult to approach closely. However, they have the unfortunate habit of sleeping in large groups under ledges where they are accessible to spearfishermen. At night, scuba-equipped spearfishermen can wipe out entire groups at all depths they are known to sleep. Although little is known of the biology of the atuhong, they probably grow slowly and take many years to mature. This makes them highly vulnerable to overfishing. Today there are very few atuhong left, and most of these are found in the less accessible northern part of the island.
Guam Comprehensive Wildlife Conservation Strategy, 9/27/2005
