Bicolored foxface (Siganus uspi)

Classification (WoRMS)

Full classification as recorded by WoRMS: Kingdom: Animalia · Phylum: Chordata · Class: Teleostei · Order: Acanthuriformes · Family: Siganidae · Genus: Siganus.

Accepted name: Siganus uspi · Authority: Gawel & Woodland, 1974 · Taxonomic status: accepted · AphiaID: 273926.

Synonyms and superseded combinations recorded for this taxon: Lo uspi (Gawel & Woodland, 1974); Siganus uspae Gawel & Woodland, 1974.

Source: World Register of Marine Species (WoRMS) — https://www.marinespecies.org/aphia.php?p=taxdetails&id=273926 (CC BY 4.0). Accessed 2026-09-25.

Biology and life history (FishBase)

Measured values published by FishBase for Siganus uspi. Only fields the database actually holds for this species are shown; these are database values, not aquarium guidance.

Maximum length: 24 cm · Habitat zone: reef-associated · Body shape: short and / or deep · Vulnerability index: 14 of 100 · Fishery importance: commercial · Aquarium trade: commercial.

FishBase notes: Found among hard corals at the faces of drop-offs at reef edges or in deep pools inside reef crests. Juveniles form schools, adults occur in pairs. Feeds on seaweeds (Ref. 9813).

Source: FishBase species summary (SpecCode 4631) — https://www.fishbase.se/summary/Siganus-uspi.html (CC BY-NC 3.0 — non-commercial use only). Accessed 2026-09-25.

Distribution and occurrence records (GBIF)

147 georeferenced occurrence records for Siganus uspi are published through GBIF from 3 countries or marine areas. The map above plots 24 distinct locations from a sample of 147 records, omitting 4 inland records that carry an institution's coordinates rather than a collection site; it shows where the species has been observed and reported, not a modelled range.

Most records by country or area: Fiji (142); Tonga (4); New Caledonia (1).

Source: GBIF Occurrence Search (taxonKey 2390169) — https://www.gbif.org/occurrence/search?taxon_key=2390169&has_coordinate=true (records CC0 / CC BY); WoRMS distribution records (MarineRegions) — https://www.marinespecies.org/aphia.php?p=taxdetails&id=273926 (CC BY 4.0); Natural Earth 110m basemap — https://www.naturalearthdata.com/ (public domain). Accessed 2026-09-25.

Conservation status (IUCN Red List)

The IUCN Red List assesses Siganus uspi Gawel & Woodland, 1974 as Near Threatened (code NT). No trend, population estimate or threat analysis is given here, because none is available from this source without the Red List API; follow the source link for the full assessment, including its date.

Source: IUCN Red List of Threatened Species (taxon 69738927) — https://www.iucnredlist.org/species/69738927/0; GBIF IUCN Red List category endpoint (taxonKey 2390169) — https://api.gbif.org/v1/species/2390169/iucnRedListCategory. Accessed 2026-09-25.

Description and natural history (Wikipedia)

The bicolored foxface was first formally described in 1974 by Michael J. Gawel & David J. Woodland with the type locality given as Joske Reef, 3 kilometers to the west of Suva on Viti Levu, Fiji. The specific name adds a Latin possessive "i" to the initials of the University of the South Pacific as that institution facilitated the authors' studies of fishes in the South Pacific and as a thank you to the people of the region who support the University.

Description

The bicolored foxface has a laterally compressed deep body, its depth fitting roughly a little over twice into its standard length with a weakly forked caudal fin. The forward nostril opening is a very short tube which expands slightly to the rear of the nostril and it has a procumbent spine in front of the dorsal fin. Like all rabbitfishes, has 13 spines and 10 soft rays in the dorsal fin while the anal fin has 7 spines and 9 soft rays.

The fin spines hold venom glands. This species attains a maximum total length of 24 cm. The overall colour is dark purplish brown apart from the yellow pectoral fins, soft rayed part of the dorsal and anal fins, the caudal fin, and rear part of body, the delineation of the 2 colours is clear.

Distribution and habitat

The bicolored foxface has only been recorded from Fiji, although there have been reports of vagrants off New Caledonia, albeit unconfirmed. They are found at depths between 3 and 20 m in areas of hard corals on the slopes of drop-offs at the reef edges or in the deeper pools within the rest of reefs.

Biology

The bicolored foxface is a herbivore which feeds on seaweeds. The adults live in pairs while the juveniles form schools. This species produces venom in the spines of its fins. In a study of the venom of a congener it was found that rabbitfish venom was similar to the venom of stonefishes.

Conservation

The bicolored foxface is a species of shallow water which is endemic to Fiji and its population is probably very fragmented and it is apparently an uncommon to rare species. It favours coral reefsand so may be suffering from habitat loss in parts of its range which may lead to population declines. Coastal development and collection for the aquarium trade will also impact the population. The IUCN consider that because of its small range and continued habitat decline, it is assessed as Near Threatened.

The bicolored foxface is collected for the aquarium trade using drive-in nets.

Source: Wikipedia: Bicolored foxface — https://en.wikipedia.org/wiki/Bicolored_foxface (CC BY-SA 4.0). Accessed 2026-09-25.