Toothy Jawfish

Toothy Jawfish, Opistognathus brochus

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

The Toothy Jawfish have moderately elongated slender tapering bodies. They have a light gray or brownish coloration with additional details 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 dorsal fin has 11 spines and 13 rays (a key to identification), and their pelvic fin has a long second ray. They have 23 to 26 gill rakers and their body is covered with scales.

The Toothy Jawfish are a relatively deep water species found at depths between 180 and 290 feet with the “catch” below extending the previously known depth range of 270 feet. They live in buried sandy or rubble substrates adjacent to coral or rocky reefs. They reach a maximum standard length of 5.9 cm (2.3 inches) with the “catch” below 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. They are a very rare and obscure species and very little is known about their behavioral patterns.

In Mexican waters the Toothy Jawfish have 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; the previously known southerly range was at La Paz.

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).

The Toothy Jawfish is too small and too obscure to be of interest to most.

Toothy Jawfish

 

 

 

 

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, CA.