Smallmouth grunt

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Smallmouth grunt. Photo by Paul Young. underwater.org

The smallmouth grunt (scientific name: Haemulon chrysargyreum) is a member of the grunt family (Family Haemulidae) that live on coral reefs in the Western Atlantic Ocean and Caribbean Sea.  Grunts derive their name from the make grunting sound they make with their pharylgeal teeth.


caption Smallmouth grunt. Source: Florent Charpin/www.reefguide.org


Scientific Classification

Kingdom: Animalia (Animals)
Phylum:--- Chordata
Class:------ Osteichthyes (Bony Fishes)
Order:-------- Perciformes
Family:-------- Haemulidae (Grunts)
Species:----------Haemulon chrysargyreum (Günther, 1859)

Physical Description

Also known by the common name banana grunt, the smallmouth grunt may range from 17 to 23 centimeters in length. Individuals of this species have an elongated cylindrical body with a forked tail and have a series of five or six yellow stripes running horizontally down their body on a silver background.   They have a yellow tails and dorsal fins. Smallmouth grunts claim their common name because their mouths are smaller than other grunts.


They have a subtropical distribution.  In the Western Atlantic they are found from southern Florida throughout the Caribbean Sea as far south as Brazil.


They are found on coral reefs in water depths of zero to 30 meters.   They are usually observed swimming over sand and rock bottoms near the reef, often in the shelter of the branches of staghorn and elkhorn coral. Juveniles are often found in seagrass beds.

Feeding Behavior

Smallmouth grunts are generalist carnivores that feed on plankton, copepods, mollusks, and shrimps. They hang around the reef during the daylight hours. After sunset, they travel to open water where they feed.


Smallmouth grunts feed at night and spend their days hiding under ledges of within the braches of elkhorn coral and staghorn coral. The ocassionally form large schools on coral reefs,


Smallmouth grunts are pelagic spawners.  Their larvae enter the planktonic stage before settling in nursery area such as shallow back reefs or seagrass beds. 


Smallmouth grunts may occasionally form schools with yellow goatfish, a species similar and size and shape to the yellow goatfish.  This association has been proposed to be an example of “social protective mimicry” because both species are protected from predators while in these mixed-species schools.


Studies at the Saba Reef, one of the richest fish assemblages in the Caribbean Basin, have indicated the chief threats to Haemulon  chrysargyreum and other reef fishes are overfishing and the residual impacts of the particular chemical dispersant used by the USA in the aftermath of the Deepwater Horizon oil spill; this chemical has high persistence and known toxicity to a gamut of marine fauna. Studies by Burke et al. suggest that concentrations of dispersant and other water pollutants are of particular concern in critical lagoon nurseries; these studies suggest that the toxicity of residual dispersant may be much more significant to reef fishes than the actual petroleum release of an underwater oil spill. The dispersant used in the Deepwater Horizon oil spill, Corexit 9500, is known to be much more toxic than the petroleum chemicals it is meant to disperse; moreover, the combined toxicity of Corexit 9500 and petroleum is more toxic to juvenile fish than either chemical set by itself.

Conservation Status

Smallmouth grunts are not considered to be a taxon at risk

References and Further Reading

  • J.S.Burke, W.J.Kenworthy and L.L.Wood. 2009. Ontogenetic patterns of concentration indicate lagoon nurseries are essential to common grunts stocks in a Puerto Rican bay. Worldwide Science.org
  • Jeffrey T. Williams, Kent E. Carpenter, James L. Van Tassell, Paul Hoetjes, Wes Toller, Peter Etnoyer, Michael Smith. 2010. Biodiversity Assessment of the Fishes of Saba Bank Atoll, Netherlands Antilles. PloS One. 5(5): e10676.
  • Encyclopedia of Life. Species curator: C.Michael Hogan. 2011.Haemulon chrysargyreum Günther, 1859  EOL
  • Haemulon chrysargyreum, Smallmouth Grunt
  • P.Humann and N.Deloach (Editor) 1994. Reef Fish Identification: Florida, Caribbean, Bahamas. New World Publications, Inc. Jacksonville, FL. ISBN: 1878348078
  • N.Deloach. 1999. Reef Fish Behavior, Florida, Caribbean, Bahamas. New World Publications, Inc. Jacksonville, FL. ISBN: 1878348280
  • Laurier Lincoln Schramm. 2000. Surfactants: fundamentals and applications in the petroleum industry. Cambridge University Press. 621 pages


McGinley, M. (2011). Smallmouth grunt. Retrieved from http://www.eoearth.org/view/article/156049


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