Many-spined butterflyfish

Lore & Background

The many-spined butterflyfish was first formally described in 1975 by American ichthyologist John Ernest Randall, with the type locality given as the Patch reef off the Gannet Ridge on the northern side of Pitcairn Island. Its common names refer to the numerous spines in its dorsal fin, which number 14 to 16, and the 5 spines in its anal fin. The species is a rather drab uniform grey colour, with a maximum recorded length of 20.8 centimetres.

This butterflyfish is found only around a few island groups in the southern Pacific Ocean: the British overseas territory of Pitcairn Island, Easter Island in Chile, and a single island in the Austral Islands, Rurutu, in French Polynesia. It occurs on deep seaward coral reefs, where it aggregates into schools varying in size from small to large in the middle of the water column at depths between 30 and 50 metres. It feeds on plankton and is an oviparous species in which males and females form pairs for breeding.

Reader's Guide

The many-spined butterflyfish is almost unknown in the aquarium trade, making it a rare sight for hobbyists. Its limited distribution—restricted to three island groups in the southern Pacific—and its deep-reef habitat contribute to its obscurity. Local fishermen collect this species for food using spears and the piscicide rotenone, indicating its use as a subsistence resource rather than a commercial one. The species was described relatively recently, in 1975, by John Ernest Randall, a prominent ichthyologist, which underscores how little was known about deep-reef butterflyfishes until late in the 20th century. Its drab grey coloration and schooling behavior in the middle of the water column distinguish it from more colorful, shallow-water relatives. The species' reliance on plankton and its pair-bonding breeding strategy are typical of many butterflyfishes, but its restricted range and deep habitat make it ecologically distinct. The use of rotenone for collection highlights traditional fishing methods in the region. Overall, the many-spined butterflyfish remains a little-known species, significant primarily for its biogeographic isolation and the limited human interactions it has.

Did You Know?

• The many-spined butterflyfish has 14-16 spines in its dorsal fin and 5 spines in its anal fin.
• It is found only around Pitcairn Island, Easter Island, and Rurutu in the Austral Islands.