Smallmouth grunt (Brachygenys chrysargyrea)

Classification (WoRMS)

Full classification as recorded by WoRMS: Kingdom: Animalia · Phylum: Chordata · Class: Teleostei · Order: Eupercaria incertae sedis · Family: Haemulidae · Genus: Brachygenys.

Accepted name: Brachygenys chrysargyrea · Authority: (Günther, 1859) · Taxonomic status: accepted · AphiaID: 1841028.

Synonyms and superseded combinations recorded for this taxon: Brachygenys chrysargyreum (Günther, 1859); Brachygenys chrysargyreus (Günther, 1859); Brachygenys taeniata (Poey, 1860); Haemulon chrysargyreum Günther, 1859; Haemulon serrula (Cuvier, 1830); Haemulon taeniatum Poey, 1860; Pristipoma serrula Cuvier, 1830.

Source: World Register of Marine Species (WoRMS) — https://www.marinespecies.org/aphia.php?p=taxdetails&id=1841028 (CC BY 4.0). Accessed 2026-09-23.

Biology and life history (FishBase)

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

Maximum length: 23 cm · Common length: 17 cm · Depth range: 0–25 m · Habitat zone: reef-associated · Body shape: fusiform / normal · Vulnerability index: 13 of 100 · Fishery importance: minor commercial · Aquarium trade: public aquariums.

FishBase notes: Inhabits exposed rocky areas and coral reefs. Often near elkhorn and staghorn corals (Ref. 9710). Commonly found in schools. Juveniles are encountered in Thalassia beds (Ref. 9626). Adults are observed in coral reefs during the day but enters open waters at night to feed on mainly on plankton (Ref. 9626), but also on small crustaceans and mollusks. Marketed fresh (Ref. 3798).

Source: FishBase species summary (SpecCode 1134) — https://www.fishbase.se/summary/Brachygenys-chrysargyrea.html (CC BY-NC 3.0 — non-commercial use only). Accessed 2026-09-23.

Distribution and occurrence records (GBIF)

1,231 georeferenced occurrence records for Brachygenys chrysargyrea are published through GBIF from 33 countries or marine areas. The map above plots 101 distinct locations from a sample of 1,231 records, omitting 20 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: United States of America (265); Bonaire, Sint Eustatius and Saba (239); Martinique (122); Mexico (69); Guadeloupe (59).

The full country table, WoRMS marine regions and the sampling notes are on this species' Distribution page.

Source: GBIF Occurrence Search (taxonKey 2382527) — https://www.gbif.org/occurrence/search?taxon_key=2382527&has_coordinate=true (records CC0 / CC BY); WoRMS distribution records (MarineRegions) — https://www.marinespecies.org/aphia.php?p=taxdetails&id=1841028 (CC BY 4.0); Natural Earth 110m basemap — https://www.naturalearthdata.com/ (public domain). Accessed 2026-09-23.

Conservation status (IUCN Red List)

The IUCN Red List assesses Brachygenys chrysargyreus Günther, 1859 as Least Concern (code LC). 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 194417_1) — https://www.iucnredlist.org/species/194417_1/0; GBIF IUCN Red List category endpoint (taxonKey 2382527) — https://api.gbif.org/v1/species/2382527/iucnRedListCategory. Accessed 2026-09-23.

Description and natural history (Wikipedia)

B. chrysargyrea is a small fish that can reach a maximum length of 23 cm, but a length of 17 cm is typical. It has a short snout with an almost horizontal mouth which is small, the jaws normally not extending as far as the front margin of the pupil. The inside of the mouth is red. It has a laterally compressed body with a forked caudal fin. Its background color is silver with five bronze-yellow horizontal lines on its sides.All fins, other than the pectoral fins are partially or completely yellow. The dorsal fin contains 12 spines and 13 soft rays while the anal fin has 3 spines and 9–10 soft rays.

B. chrysargyrea is widespread throughout the western Atlantic Ocean from south Florida to the cost of Brazil, including the Gulf of Mexico and the Caribbean Sea.

The adults inhabit exposed areas of coral reefs and rocky coasts up to 25 m deep. Juveniles prefer hard substrates and around coral reefs or Thalassia sea grass beds.

B. chrysargyrea is nocturnal, spending the daytime in schools near reefs or rocks and disperse at night to feed at the open sea.

Their diet consists mainly of plankton, but also small crustaceans and other mollusks. Off the Fernando de Noronha Islands of northeastern Brazil it has been observed that this species and the yellow goatfish (Mulloidichthys martinicus) mimic each other in colour and shape, allowing them to form mixed schools, which improves their ability to avoid predators that rely on vision for hunting.

B. chrysargyrea was first formally described in 1859 by German-born British ichthyologist and herpetologist Albert Günther (1830–1914), with the type locality given as Trinidad. The specific name is a compound of the Greek chrysos meaning "gold" and argyreum meaning "silvery", a reference to the silvery background colour marked with gold streaks and stripes.

Cuban zoologist Felipe Poey (1799–1891) described a species of grunt he named Haemulon taeniatum in 1860. He placed this species in the new genus Brachygenys in 1868. Poey's taxon was later ascertained to be a junior synonym of Günther's. Molecular studies have suggested that Haemulon sensu lato is polyphyletic because they showed that Haemulon chrysargyreum clustered with Xenistius californiensis, rendering Haemulon as polyphyletic if Xenistius was not included. The genus Brachygenys, was revived to include Xenistius californiensis, Haemulon chrysargyreum, Xenistius peruanus and Xenocys jessiae. As Brachygenys is feminine the specific name is feminised to chrysargyrea.

B. chrysargyrea is caught as bycatch in traps, the fish caught being sold fresh. It is rare in the aquarium trade but is commoner in public aquarium displays.

Source: Wikipedia: Brachygenys chrysargyrea — https://en.wikipedia.org/wiki/Brachygenys_chrysargyrea (CC BY-SA 4.0). Accessed 2026-09-23.

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