Brighteye Cusk Eel, Ophidion iris
Brighteyed Cusk Eel, Ophidion iris. Fish caught by the commercial fishermen of the greater Los Cabos area, Baja California Sur, December 2010. Size: 19.1 cm (7.5 inches). Tail: 62% of TL. Identification courtesy of Dr. Robert N. Lea, Monterey, California.
The Brighteye Cusk Eel, Ophidion iris, is a member of the Cusk Eel or Ophidiidae Family, and is known in Mexico as congriperla arcoiris. Globally, there are twenty-seven species in the genus Ophidion, of which seven are found in Mexican waters, two in the Atlantic and five in the Pacific Ocean.
The Brighteye Cusk Eel has an elongated body that tapers toward the rear. They are a uniform pale brown in color that is lighter below. The front two-thirds of the anal and dorsal fins have narrow dark margins. The heads are compressed with small blunt projecting snouts with a slightly oblique mouth. The anal fin has a long base; the caudal fin is pointed and continuous with the anal and dorsal fins; the dorsal fin has a long base and originates before the anal fin; and the pelvic fins are 1.2 x 1.8 times the length of the pectoral fins and each has a two-rayed filament that is found under the throat. The head is scaleless, however, the body is covered with small smooth elongated scales. A key to identification is the gill raker count – 6 to 7 in total with the lower 4th and 5th being longer.
The Brighteye Cusk Eel is a demersal species that is found over and within sandy and mud bottoms at depths up to 110 m (280 feet). They reach a maximum 25 cm (9.8 inches) in length. They are rarely seen by humans because they hide in caves during the day time and emerge to feed on crustaceans, polychaete worms, small clams and other invertebrates at night. The Brighteye Cusk Eel 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 Brighteye Cusk Eel is a resident of Mexican waters of the Pacific Ocean but has a limited distribution historically only being documented in the lower three-fourths of the Sea of Cortez. The fish pictured above documents a northerly range extension into the Pacific along the the southwest coast of Baja.
The Brighteye Cusk Eel is most likely confused with the Basketweave Cusk Eel, Ophidion scrippsae (6-11 gill rakers, lower fourth to eighth are long; criss-cross lines along scale rows).
From a conservation perspective the Brighteye Cusk Eel is currently considered to be of Least Concern with stable, widely distributed populations. They caught as a by-catch of deep water trawlers and by hook and line by commercial fishermen in the greater Los Cabos area but are too rare and too small to be of commercial interest. They are seldom seen by humans and are of limited interest to most.