Longspine grunt (Rhencus macracanthus)

Classification (WoRMS)

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

Accepted name: Rhencus macracanthus · Authority: (Günther, 1864) · Taxonomic status: accepted · AphiaID: 1577352.

Synonyms and superseded combinations recorded for this taxon: Paraconodon orthopristis Breder, 1936; Pomadasis burro Starks, 1906; Pomadasys andrei (Sauvage, 1879); Pomadasys macracanthus (Günther, 1864); Pristipoma andrei Sauvage, 1879; Pristipoma macracanthum Günther, 1864; Pristipoma macracanthus Günther, 1864.

Source: World Register of Marine Species (WoRMS) — https://www.marinespecies.org/aphia.php?p=taxdetails&id=1577352 (CC BY 4.0). Accessed 2026-09-23.

Biology and life history (FishBase)

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

Maximum length: 37 cm · Common length: 20 cm · Depth range: 1–30 m · Habitat zone: benthopelagic · Body shape: fusiform / normal · Vulnerability index: 27 of 100 · Fishery importance: commercial · Aquarium trade: never/rarely.

FishBase notes: Found near the littoral zone of coastal waters (Ref. 9114). Penetrates estuaries (Ref. 9114). Marketed fresh (Ref. 9114). Depth range assumed (RF).

Source: FishBase species summary (SpecCode 13738) — https://www.fishbase.se/summary/Rhencus-macracanthus.html (CC BY-NC 3.0 — non-commercial use only). Accessed 2026-09-23.

Distribution and occurrence records (GBIF)

46 georeferenced occurrence records for Rhencus macracanthus are published through GBIF from 3 countries or marine areas. The map above plots 4 distinct locations from a sample of 46 records, omitting 22 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: Mexico (36); Ecuador (6); Panama (4).

Source: GBIF Occurrence Search (taxonKey 11858866) — https://www.gbif.org/occurrence/search?taxon_key=11858866&has_coordinate=true (records CC0 / CC BY); WoRMS distribution records (MarineRegions) — https://www.marinespecies.org/aphia.php?p=taxdetails&id=1577352 (CC BY 4.0); Natural Earth 110m basemap — https://www.naturalearthdata.com/ (public domain). Accessed 2026-09-23.

Description and natural history (Wikipedia)

Pomadasys macracanthus has a body which is oblong and laterally compressed, its depth being over one-third its standard length. The overall colour is silvery marked with 4 or 5 vague dark bars on their flanks, these may have faded completely in adults, and a dark spot on the upper angle of the operculum. The dorsal profile of the head is straight and the small mouth is positioned terminally. The dorsal fin is deeply notched and contains 12-14 spines and 13-14 soft rays while the anal fin contains 3 spines and 7-8 soft rays. The pectoral fins are rather long extending as far as the anus. They whole fish is covered with scales. This species attains a maximum total length of 37 cm, although 20 cm is more typical.

Pomadasys macracanthus is found in the eastern Pacific Ocean. Its range extends from southern Baja California and the Gulf of California, south along the Pacific coast of Central and South America to Ecuador.

Pomadasys macracanthus primarily lives in the littoral zone of the coastal marine environment, but has been known to enter estuaries. In the Golfo de Nicoya in Costa Rica the longspined grunt is regarded as an transient species which visits the area to use two mangrove areas. Their diet consists of mobile, benthic invertebrates such as cephalopods, gastropods, crustaceans and annelids.

Pomadasys macracanthus was first formally described in 1864 as Pristipoma macracanthum by the German-born British zoologist Albert Günther (1830-1914) with the type locality given as Chiapas in Mexico. The specific name macracanthus means "long" or "strong" spined. This species is placed in the genus Rhencus by some authorities, along with Pomadasys panamensis.

Pomadasys macracanthus is important to commercial fisheries, especially in the Gulf of Montijo in Panama. Although the longspined grunt is not a true perch, it has been marketed for classroom science dissections in North America as the "Mexican gray perch," offering an apparent marine counterpart to the commonly dissected yellow perch.

Source: Wikipedia: Pomadasys macracanthus — https://en.wikipedia.org/wiki/Pomadasys_macracanthus (CC BY-SA 4.0). Accessed 2026-09-23.