Toothy Jawfish, Opistognathus brochus

Toothy Jawfish, Opistognathus brochus. Fish caught from coastal waters off Point Palmilla, Baja California Sur, April 2014. Regurgitated by an Olive Grouper, Epinephelus cifuentesi. Length: 7.0 cm (2.8 inches). Identification courtesy of H.J. Walker, Jr., Scripps Institution of Oceanography, La Jolla, California.

The Toothy Jawfish, Opistognathus brochus, is a member of the Jawfish or Opistognathidae Family, that is known in Mexico as bocón dientudo. Globally, there are forty-three species in the genus Opistognathus, of which thirteen are found in Mexican waters, six in the Atlantic and seven in the Pacific Ocean.

The Toothy Jawfish has moderately elongated slender tapering body. They have a light gray or brownish coloration with additional details are lacking – fish within scientific collections are only preserved specimens and the “catch” photographed below is of a partially digested regurgitated fish. They have rounded heads with disproportionately large dark eyes and large mouths that extend well past the eyes. They have numerous plainly visible teeth on both jaws (pictured below). Their anal fin is black, their caudal fin is rounded with a dark bar at its base and a dusky bar mid-fin. Their anal fin has 3 spines and 12 rays; their caudal fin is rounded; their dorsal fin has 11 spines and 13 rays; and, their pelvic fins have a long second ray. They have 23 to 26 gill rakers. Their body is covered with scales.

The Toothy Jawfish are a relatively deep water species found at depths between 55 m (180 feet) and 88 m (290 feet) with the “catch” below extending the previously known depth range of 82 m (270 feet). They live in buried sandy or rubble substrates adjacent to coral or rocky reefs. They reach a maximum of 5.9 cm (2.3 inches) in length with the “catch” photographed above extending the previously known length of 5.4 cm (2.1 inches). It is assumed that like other Jawfish they live in elaborate burrows that are self-constructed by utilizing their mouths and powerful jaws to excavate sand, small stones, and medium-sized rocks and that they feed primarily on benthic and planktonic invertebrates. In addition, like other Jawfish it is assumed that they exhibit the unusual habit of oral egg incubation. The Toothy Jawfish 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.

In Mexican waters the Toothy Jawfish is a resident of the Pacific but has a limited distribution being found only throughout the Sea of Cortez with the “catch” below extending the southern range to just north of Cabo San Lucas, Baja California Sur; the previously known southerly range was to La Paz, Baja California Sur.

The Toothy Jawfish is most likely confused with the Mexican Jawfish, Opistognathus walkeri (uniform gray color; long mouth that extends past the operculum; very limited range in the northern Sea of Cortez).

From a conservation perspective the Toothy Jawfish has not been formally evaluations. They are exceedingly rare, small in stature and seldom seen by humans.