Chocolate Tonguefish, Symphurus callopterus
Chocolate Tonguefish, Symphurus callopterus. Fish provided by the commercial fishermen in the greater Los Cabos area, Baja California Sur, January 2011. Length: 12.5 cm (4.9 inches).
The Chocolate Tonguefish, Symphurus callopterus, is a member of the Tonguefish or Cynoglossidae Family, and is known in Mexico as lengua chocolate. There are sixty-six global members of the genus Symphurus, twenty-three of which are found in Mexican waters, nine in the Atlantic and fourteen in the Pacific Ocean.
The Chocolate Tounguefish have elongated oval flat bodies that taper to a pointed tail with a depth that is 28% to 32% of standard length. They have a brown coloration with nine to eleven subtle wide dark bands across their body and a dark blotch on the lower half of their gill cover. The rear portions of their anal and dorsal fins have ten to nineteen rectangular black blotches alternating with clear areas. Their caudal fin is black or with black blotches. Their ventral or blind side is cream color. Their head has a rounded snout with a small curved mouth and small beady eyes on the left side closely set together 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 91 to 98 rays; their dorsal fin has 105 to 114 rays and originates above the upper eye; they do not have pectoral fins; and they have only a left pelvic fin. Their body is covered with rough scales. They do not have a lateral line.
The Chocolate Tonguefish is found over and within soft sandy and muddy bottoms at depths between 20 m (65 feet) and 290 m (950 feet). They are uniquely colored to blend with the substratum. They reach a maximum of 16.2 cm (6.4 inches) in length. They feed on small fish and crustaceans. The Chocolate Tonguefish 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.
The Chocolate Tonguefish is a resident of Mexican waters of the Pacific Ocean has a limited range being found from Magdalena Bay to Cabo San Lucas, Baja Calfiornia Sur, along the southwest coast of Baja and from Mazatlán, Sinaloa, south to Guatemala along the coast of the mainland.
The Chocolate Tonguefish can be confused with the Halfspotted Tonguefish, Symphurus atramentatus, the Banded Tonguefish, Symphurus fasciolaris, and the Whitetail Tonguefish, Symphurus oligomerus, however each of these lack the blotching pattern at the base of their anal and dorsal fins.
From a conservation perspective the Chocolate Tonguefish is currently considered to be of Least Concern with stable, widely distributed populations. They are small in stature and seldom seen by humans, thus of limited interest to most.