Smallmouth Grunt, Haemulon chrysargyreum

Smallmouth Grunt, Haemulon chrysargyreum, Juvenile. Fish caught in coastal waters within the Bahia Honda State Park, Big Pine Key, Florida, April 2019. Length: 12.2 cm (4.8 inches). Catch, photograph and identification courtesy of Luke Ovgard, Klamath Falls, Oregon.

Smallmouth Grunt, Haemulon chrysargyreum, Juvenile. Fish caught from coastal waters off Silver Palm Park, Boca Raton, Florida, January 2016. Length: 12.7 cm (5.0 inches). Catch, photograph and identification courtesy of George Brinkman, Guelph, Ontario, Canada.

Smallmouth Grunt, Haemulon chrysargyreum, Juvenile. Fish caught from coastal waters off Key Largo, Florida, August 2018. Length:  12.8 cm (5.0 inches). Catch, photograph, and identification courtesy of Josh Leisen (joshadventures.com), Gaylord, Michigan.

Smallmouth Grunt, Haemulon chrysargyreum. Fish caught from coastal waters off Caye Ambergris, Belize, June 2013. Length: 13 cm (5.1 inches). Catch, photograph and identification courtesy of Eli (obsessiveangling.wordpress.com).

Smallmouth Grunt, Haemulon chrysargyreum. Fish caught from coastal waters off Key West, Florida, June 2015. Length: 18 cm (7.1 inches). Catch, photograph and identification courtesy of Dean Kimberly, Atlanta, Georgia.

Smallmouth Grunt, Haemulon chrysargyreum. Fish caught in coastal waters off Key Largo, Florida, April 2019. Length: 19 cm (7.5 inches). Catch, photograph and identification courtesy of Luke Ovgard, Klamath Falls, Oregon.

Smallmouth Grunt, Haemulon chrysargyreum. Underwater photograph taken in coastal waters of Yal-Ku, Quintana Roo, April 2016. Photograph courtesy of Juan Rojo, Akumal.

Smallmouth Grunt, Haemulon chrysargyreum. Underwater photograph taken in coastal waters off Bonaire, December 2019. Photograph courtesy of Bob Hillis, Ivins, Utah.

The Smallmouth Grunt, Haemulon chrysargyreum, is a member of the Grunt or Haemulidae Family, and is known in Mexico as ronco boquichica. Globally, there are twenty-one species in the genus Haemulon, and all twenty-one are found in Mexican waters, fourteen in the Atlantic and seven in the Pacific Ocean.

The Smallmouth Grunt has a longer and thinner body than most Grunts with a depth that is 27% to 31% of standard length. They have an overall silvery-gray appearance and are characterized by a series of 5 or 6 six yellow-bronze straight stripes evenly sized and spaced on their sides. All their fins, except for the pectoral fins, are yellowish-brown. The inside of their mouth is red. They have a blunt head with a convex upper profile, a short snout, a small horizontal mouth that opens at the front and ends before the eyes, and finely serrated gill covers that are spineless. Their anal fin has 3 spines, with the second and third being similar, and 9 or 10 rays; their caudal fin is forked; and their dorsal fin has 12 spines, a small to modest notch in the middle, and 12 to 14 rays. They have 30 to 33 gill rakers. Their body is covered with rough scales.

The Smallmouth Grunt is a schooling species that is found inshore sheltering in Elkhorn and Staghorn Corals and in rocky reefs during the day; they move to open water at night to depths up to 30 m (100 feet). Juveniles are found within seagrass beds. They reach a maximum of 23.0 cm (9.1 inches) in length. They feed primarily on plankton but also on small crustaceans and mollusks. The Smallmouth Grunt  is poorly studied with very limited information available about their lifestyle and behavioral patterns including specific details on age, growth, longevity, movement patterns, diet, habitat use, and reproduction.

The Smallmouth Grunt is a resident of all Mexican waters of the Atlantic Ocean including the Gulf of Mexico and the Caribbean, however, they are less abundant in the western portions of the Gulf of Mexico.

The Smallmouth Grunt can be confused with the French Grunt, Haemulon flavolineatum (lacks bars on sides), the Striped Grunt, Haemulon striatum (stripes of unequal widths with the ventral stripe being widest), and the Tomtate, Haemulon aurolineatum (lacks bars on sides).

From a conservation perspective the Smallmouth Grunt is currently considered to be of Least Concern with stable, widely distributed populations. They are caught and used by recreational anglers as live bait. Although very small in stature, they are considered a quality food fish and are marketed fresh. They have recently been raised in captivity via aquaculture with the objective of using them to rebuild reefs. They can be found on a limited basis in large public aquariums and they are more peaceful than other grunts, however, they are difficult to maintain and many are unable to survive the first week in captivity.