Chaetodon pelewensis

Lore & Background

Chaetodon pelewensis was first formally described in 1868 by Austrian ichthyologist Rudolf Kner, with the type locality given as Palau (Pelew Inseln) in the western Pacific, though this is considered an error and the correct type locality is probably the Society Islands. The specific name reflects this erroneous designation. The species is placed in the subgenus Exornator; if the genus Chaetodon is split up, Exornator might become a subgenus of Lepidochaetodon.

The fish has a dusky yellow body with diagonal stripes across the body and a black-margined gold vertical bar through the eye. A black spot is present on the head, and the stripes break up into spots toward the head and on the lower flanks. The fin margins are bright yellow, and the base of the caudal fin is bright orange. It attains a maximum total length of 12.5 cm. The dorsal fin has 13-14 spines and 22-25 soft rays, while the anal fin has 3 spines and 17-18 soft rays.

Chaetodon pelewensis is found across the southern Pacific Ocean from Papua New Guinea to the Tuamotu Archipelago. It is abundant on the Great Barrier Reef and in the Coral Sea, and in Australia it extends as far south as central New South Wales and Lord Howe Island. It inhabits coral reefs at depths of at least 45 meters, feeding largely on coral polyps and some benthic invertebrates. The species is oviparous and monogamous, breeding in pairs. Occasionally it forms mixed pairs with the spotband butterflyfish (C. punctatofasciatus), and these species are known to hybridise.

Reader's Guide

Chaetodon pelewensis is commonly found in the aquarium trade, with over 12,000 individuals traded between 1988 and 2002. Its popularity in aquaria stems from its striking coloration—dusky yellow body with diagonal stripes, black-margined gold eye bar, and bright yellow fin margins—making it a visually appealing species for marine hobbyists. Ecologically, it plays a role in coral reef ecosystems as a feeder on coral polyps and benthic invertebrates. Its monogamous breeding behavior and occasional hybridization with Chaetodon punctatofasciatus highlight its reproductive and evolutionary dynamics. The species' abundance on the Great Barrier Reef and in the Coral Sea underscores its significance in these regions. The taxonomic uncertainty regarding its type locality and subgeneric placement adds to its scientific interest, reflecting the complexities of butterflyfish classification. Overall, Chaetodon pelewensis is a well-documented species in both natural history and the aquarium trade, contributing to our understanding of reef fish diversity and human interaction with marine life.

Did You Know?

• Chaetodon pelewensis was first described in 1868 by Austrian ichthyologist Rudolf Kner.
• The type locality was erroneously given as Palau (Pelew Inseln); the correct locality is probably the Society Islands.
• This species occasionally forms mixed pairs with the spotband butterflyfish (C. punctatofasciatus) and can hybridize with it.
• Over 12,000 individuals of this species were traded in the aquarium industry between 1988 and 2002.