Darkcheek Tonguefish

Darkcheek Tonguefish, Symphurus chabanaudi

The Darkcheek Tonguefish, Symphurus chabanaudi, whose common Spanish name is lengua cachet prieto, is a species in the Tonguefish or Cynoglossidae Family, known collectively as lenguas in Mexico. This fish was introduced in 1990 as a new species. Globally, there are sixty-six species in the genus Symphurus, twenty-five are found in Mexican waters, eleven in the Atlantic and fourteen in the Pacific.

The Darkcheek Tonguefish have elongated oval flat bodies that taper to a pointed tail and a body depth that is 23 to 27% of standard length. They are left-eyed fish with no lateral line. They are light brown with five to eight subtle wide dark bands across their body and a large dark blotch on their gill cover (after which they are named). Their blind side is cream color. Their anal and dorsal fins are dusky and their caudal fin is also dusky with a darker tip. Their head has a rounded snout with a small curved mouth and small beady eyes set closely together on the left side with the upper eye being slightly in front of the lower eye. Their anal and dorsal fins are confluent with the pointed caudal fin. Their anal fin has 82 to 92 rays. Their dorsal fin originates above the upper eye and has 98 to 109 rays. They only have a left pelvic fin. They have no pectoral fins and no lateral lines. Their body is covered with small rough scales.

The Darkcheek Tonguefish are found over and within soft sandy and muddy bottoms at depths up to 200 feet. They reach a maximum length of 24.0 cm (9.4 inches). They are uniquely colored to blend with the substratum. They feed on small fish and crustaceans. They are a poorly studied species and very little is known about their behavioral patterns.

In Mexican waters the Darkcheek Tonguefish has a limited range being found only in the northern 70% of the Sea of Cortez and along the entire west coast of the mainland south to Guatemala.

The Darkcheek Tonguefish can be confused with a series of other Mexican Tonguefish of the Pacific including the California Tonguefish, Symphurus atricaudus (nine incomplete bars on body), the Drab Tonguefish, Symphurus melanurus (plain; no bars), the Elongate Tonguefish, Symphurus elongatus (gill cover area not dark), the Halfstriped Tonguefish, Symphurus prolatinaris (5 to 15 incomplete bars), and the Yellow Tonguefish, Symphurus williamsi (numerous faint thin complete bars).

The Darkcheek Tonguefish are small and seldom seen by humans, thus of limited interest to most. They are caught primarily as a by-catch of deep water shrimp trawlers and are normally discarded.

Darkedge Tonguefish, Symphurus chabanaudi. Fish provided by the commercial fishermen of Bahía Kino, Sonora, March 2015. Length: 19.3 cm (7.6 inches). Photo and identification courtesy of Maria Johnson, Prescott College Kino Bay Center, Kino Bay, Sonora.