When exploring the vast and rich underwater world of Palau, we are inundated by fantastic movement and a myriad of spectacular colors. The abundance and variety of the small fishes found on the reef seems to create a setting of a busy metropolis. As our senses become adapted to the overwhelming amount of movement and color, we can begin to distinguish different types of fishes swimming along and within the reef. Some of the more conspicuous inhabitants of this thriving metropolis are the colorful and dazzling butterflyfishes. They are members of the scientific family Chaetontidae, which contain 10 genera with 116 species. The Indo-Pacific region, which comprises the waters from East Africa to the Americas, can account for 90% of the species. At least 44 species in 5 genera occur in Micronesia. The Pyramid Butterflyfish (Hemitaurichthys polylepis) is among those found in Micronesian Waters.

            The butterflyfish family contains a colorful collection of fishes with diverse body patterns. They have deep, highly laterally compressed bodies with one continuous dorsal fin. They have small protractile mouths and ctenoid (spiny edged) scales. These fishes are diurnal; in other words, they are active and foraging during the day and rest on the bottom or among the corals during the night. Some butterflyfish, especially those that feed on coral polyps, can be very territorial and patrol a home range either alone or with a mate. Others, like the Pyramid Butterflyfish, are mid-water to deep pelagic planktivores and may be seen swimming together in spectacular numbers.

            Here among the many wondrous exhibits at the Palau Aquarium are several species of butterflyfishes. Currently, we have one pair of Pyramid Butterflyfish located in the Outer Reef Exhibit and they can be seen always swimming together. These butterflyfish bear a white pyramid-shaped patch on each side. As it grows its head changes color form yellow to brown. In the wild, they can be seen in large groups at almost every wall or drop-off in Palauan waters, such as Blue Corner. They tend to congregate in clear oceanic waters that are exposed to strong currents. Here, they can find an abundant supply of food. Their shoaling (schooling) behavior is beneficial for a variety of reasons. First, congregating in large numbers helps maximize their use of their planktonic food source. Second, there is safety in numbers. Last, their large numbers provide an ample supply of mating partners. Enjoy our underwater metropolis and make sure you watch out for traffic.

The Pyramid Butterflyfish
(Hemitaurichthys polylepis)

Further Reading:

Allen, R. A. 1998. A Guide to Angelfishes & Butterflyfishes, pp 250, Odyssey Publishing/Tropical Reef Research, USA/Aust.
Myers, R. F. 1999. Micronesian Reef Fishes: A Comprehensive Guide to the Coral Reef Fishes of Micronesia, pp 239, Coral Graphics, Guam

Publication No. 03-002
P. O. Box 7086
Koror, Palau 96940
Tel. No.: 680-488-6950; FAX: 680-488-6951
E-mail: picrc@picrc.org; Website; www.picrc.org