Silvergray Grunt

Silvergray Grunt, Anisotremus caesius

The Silvergray Grunt, Anisotremus caesius, whose common Spanish name is burro mojarro, is a species in the Grunt or Haemulidae Family, known collectively as burros in Mexico. Globally, there are ten three species in the genus Anisotremus, six of which are found in Mexican waters, two in the Atlantic and two in the Pacific.

The Silvergray Grunts have deep compressed bodies with a depth that is 38 to 40% of standard length. They have an overall golden or yellowish color becoming white on their lower sides and have a broad horizontal black bar immediately behind their head. They have a high back, a short head, and a blunt small mouth with fleshy lips. All their fins have a yellow tint. Their anal fin has 3 spines, with the second being long and thick, and 9 or 10 rays. Their dorsal fin is continuous but deeply notched and has 12 spines, the fourth spine being the longest, and 15 or 16 rays. The longest dorsal spine and the second anal spine are less than one-half the head length. They have long pectoral fins that reach the anal fin origin or beyond.

The Silvergray Grunts are inshore bottom dwellers found over coral reefs, in rocky and rubble substrate, and in rocky habitats in estuaries at depths up to 80 feet. They reach a maximum length of 30 cm (12 inches). They are a very rare poorly studied species and little is known about their behavioral patterns.

In Mexican waters the Silvergray Grunts found from Mazatlán south along the west coast of the mainland to Guatemala. The fish photographed below extends this known range to the extreme southern portions of Baja.

The Silvergray Grunt cannot be confused with any other species due to their anal and dorsal fin counts.

The Silvergray Grunts are too rare and too small to be of interest to most.

Note: Juvenile Silvergray Grunts are very different in appearance from the adults, thus the picture below should be viewed accordingly.

Silvergray Grunt, Anisotremus caesius, juvenile. Fish provided by the commercial fishermen of the greater Los Cabos area, October 2011. Length: 6.0 cm (2.4 inches). Identification courtesy of H.J. Walker, Jr., Scripps Institution of Oceanography, La Jolla, CA, who believes there is a remote possibility that this might be a Blackbarred Grunt, Anisotremus dovii, also known only to the coast of the mainland which has similar “counts” noting that the adult Black Barred Grunt has a very different body shape than the Silvergray Grunt.

Silvergray Grunt, Anisotremus caesius.  Fish caught from coastal waters off Mazatlan, Sinaloa, October 2017.  Lengths:  19 cm (7.5 inches). Catch, photo and identification courtesy of Josh Leisen (, Gaylord, MI.


f065-silvergray-grunt-3Silvergray Grunt, Anisotremus caesius. Fish caught in the same location in coastal waters off Mazatlan, Sinaloa, October 2016.  Lengths:  19 cm (7.5 inches) each. Note the significantly different base color of the two fish.  Catch, photos, and identifications courtesy of George Brinkman, Guelph, Ontario, Canada.