Smallmouth Grunt

Smallmouth Grunt, Haemulon chrysargyreum

The Smallmouth Grunt, Haemulon chrysargyreum, whose common Spanish name is ronco boquichica, is a species in the Grunt or Haemulidae Family, known collectively as burros and roncadors in Mexico. 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.

The Smallmouth Grunts have longer and thinner bodies 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 five or 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 and 9 or 10 rays with the second and third spines being similar; their caudal fin is forked; and their dorsal fin is continuous with a small to modest notch in the middle, 12 spines, and 12 to 14 rays. They have 30 to 33 gill rakers and their body is covered with rough scales.

The Smallmouth Grunts are a schooling species 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 100 feet. Juveniles are found within seagrass beds. They reach a maximum length of 23.0 cm (9.1 inches). They feed primarily on plankton but also on small crustaceans and mollusks.

In Mexican waters the Smallmouth Grunts are found in all waters of the Atlantic, 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).

The Smallmouth Grunts, being more peaceful than other grunts, are utilized on a limited basis by large public aquariums, however, they are difficult to maintain and many are unable to survive the first week in captivity. They have recently been raised in captivity via aquaculture with the objective of using them to rebuild reefs. They are caught and used by recreational anglers as live bait. Although very small, they are considered a quality food fish and are marketed fresh.

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

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