Brighteye Cusk Eel, Ophidion iris
The Brighteye Cusk Eel, Ophidion iris, whose common Spanish name is congriperla acroiris, is a species in the family Ophidiidae, the Cusk Eels, known as brotula and congriperlass in Mexico. 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.
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. A key to identification is the gill raker count – 6 to 7 in total with the lower 4th and 5th being longer. The anal and dorsal fin bases are long and continuous with the pointed caudal fin with the dorsal fin being longer and originating before the anal fin. 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.
The Brighteye Cusk Eel inhabit sandy and mud bottoms and is found demersal (on the bottom) at depths up to 280 feet. They reach a maximum length of 25 cm (9.8 inches). 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 has a limited distribution in Mexican waters of the Pacific being found only in the lower three-fourths of the Sea of Cortez. The fish pictured below documents a northerly range extension into the Pacific for this species.
The Brighteye Cusk Eel is most likely confused with the Basketweave Cusk Eel, Ophidion scrippsae (6-11 gill rakers, lower 4th to 8th long; criss-cross lines along scale rows). They are obtained 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.