Armed Grunt

Armed Grunt, Conodon serrifer

The Armed Grunt, Conodon serrifer, whose common Spanish name is ronco ofensivo, is a species in the Grunt or Haemulidae Family, known collectively as burros in Mexico. Globally, there are only three species in the genus Conodon, two of which are found in Mexican waters, one in the Atlantic and one in the Pacific.

The Armed Grunts have elongated compressed bodies with a depth that is 26 to 30% of standard length. They have a silvery blue gray coloration; they have brown tinges dorsally and are white ventrally. Their head is silvery brown. They have six or seven bars on their upper sides that do not extend below their pectoral fins. All their fins are yellow with the exception of their first dorsal fin which is dusky. Their eyes are larger than their snout. Their snout has four pores, two in front and two in back. Their gill cover border is concave and strongly serrated with one or two large spines pointing backwards (after which they are named). The anal fin has 3 spines, the second being much larger than the third, and 7 or 8 rays; the caudal fin is straight or slightly concave; the dorsal fin has 12 spines and 12 or 13 rays; and, the pectoral fins are long and reach past the pelvic fin tips. Their body is covered with scales.

The Armed Grunts are found at depths between 20 and 235 feet and are caught primarily by deep water shrimp trawlers as a by-catch from near shore waters. They reach a maximum length of 30 cm (12 inches). They are a very rare poorly studied species and little is known about their behavior patterns.

In Mexico the Armed Grunt are found in all waters of the Pacific with the exception that they are absent from of the northern third of the Sea of Cortez.

Due to its coloration and marking the Armed Grunt is a fairly easy fish to identify and cannot be confused with any other species.

The Armed Grunt are of minor importance as a food fish due to their rarity and small size and if caught are normally a “catch and release.”

Armed Grunt, Conodon serrifer. Fish caught from coastal waters off Mazatlán, Sinaloa, April 2013. Length: 25 cm (10 inches). Catch, photo and identification courtesy of George Brinkman, Guelph, Ontario, Canada.

Armed Grunt, Conodon serrifer. Fish caught within Magdalena Bay, Baja California Sur, April 2016. Length: 28 cm (11 inches).