Adults are gray to yellowish brown with many small blue spots. Female bignose unicornfish have thin vertical lines behind their heads and over their body, becoming more lined with age. Males are usually fully lined to the lower part of their body and are spotted only on their backs. They develop a large nose with a thick vertical blue line, and have blue lips.
Juveniles are similar to adults but are more finely spotted, and lack the large nose.
Maximum length of 55 cm.
Habitat
Deep lagoons and seaward coral reefs at depths of 4-50 m.
Diet
Zooplankton
Life History
Like other members of the Acanthuridae family, bignose unicornfish release eggs and sperm into the water. Once fertilized eggs hatch, they go into their larvae stage.
Bignose unicornfish have a long larval stage They are strong swimmers and stay in the water column for about 90 days before settling onto reefs.
Adults are semi-pelagic because they spend some time in the open water and some time on reefs. They form schools and swim in open water next to reefs in order to feed.
The bignose unicornfish can live up to ~50 years.
IUCN Status
Least Concern
Ecosystem & Cultural Importance
Bignose unicornfish are harvested by subsistence fisheries, which involve small-scale fishing practices done by individuals for local consumption.
They have a mutually beneficial relationship with cleaner fish. Cleaner fish eat the dead skin and parasites off the bignose unicornfish.
Widespread throughout the Indo-Pacific from East Africa to French Polynesia and Hawaii, north to southern Japan, and south to the southern Great Barrier Reef and New Caledonia. In the Eastern Pacific, this species is only found in the Galapagos Islands.
The color of bignose unicornfish changes based on mood, habitat and purpose. For instance, they turn pale to help the cleaner fish find parasites. During courtship males can instantaneously turn their blue coloring into a display of iridescence.
Citations & Other Resources
Dominici-Arosemena, A., H. Molina, R. Robertson & B. Smith-Vaniz. 2012. Naso vlamingii. The IUCN Red List of Threatened Species 2012
Klanten, O. S., J. H. Choat, and L. van Herwerden. 2007. Extreme genetic diversity and temporal rather than spatial partitioning in a widely distributed coral reef fish. Marine Biology 150:659–670.
Kuiter, R. H. 1997. Guide to sea fishes of Australia. New Holland, Frenchs Forest, Australia.
Myers, R. F. 1989. Micronesian reef fishes: a practical guide to the identification of the coral reef fishes of the tropical central and western Pacific. Coral Graphics, Barrigada, Territory of Guam, U.S.A.
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