Smiling Sand Eel, Ichthyapus selachops

Smiling Sand Eel, Ichthyapus selachops. Fish provided by the commercial fishermen of the greater Los Cabos area, Baja California Sur, May 2013. Length: 31 cm (12 inches). Tail 61%. Identification courtesy of H.J. Walker, Jr., Scripps Institution of Oceanography, La Jolla, California.

The Smiling Sand Eel, Ichthyapus selachops, is a member of the Snake Eel or Ophichthidae Family, and is known in Mexico as tieso sonriente. Globally, there are five species in the genus Ichthyapus, of which two are found in Mexican waters, one in the Atlantic and one in the Pacific Ocean.

The Smiling Sand Eel has an elongated cylindrical body with a rounded cross-section that is fusiform, tapering at both ends. They have an overall creamy yellow coloration with irregular brown spots on their head and a brown stripe along their mid-side. Their head is conical with a sharply pointed snout that is broad, depressed, and overhanging. They have minute eyes and pointed teeth in a single row. Their front nostril is a flat hole (a key to identification) and their rear nostril has an irregular rim and opens into the mouth. Their gill openings are below the head on the throat. They do not have fins or scales. Their tail is long and is 62% to 64% of total length and ends in a hard finless point.

The Smiling Sand Eel is a demersal species that is a burrowing fish that spends the majority of their time half submerged within soft sandy and muddy bottoms at depths up to 30 m (100 feet). They reach a maximum of 54 cm (21 inches) in length. They feed on invertebrates and small fish. The Smiling Sand 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 Smiling Sand Eel is a resident of Mexican waters of the Pacific Ocean but have a limited distribution being found along the extreme southwest corner of the Baja, Baja California Sur, as established by the fish photographed above, along the east coast of Baja from Santa Rosalia to Cabo San Lucas, Baja California Sur, and along the coast of the mainland from Mazatlán, Sinaloa, to Guatemala.

The Smiling Sand Eel is virtually identical to and very easily confused with the Equatorial Eel, Apterichtus equatorialis (maximum length 30 cm; tubular front nostril; rear nostril is a slit in lip).

From a conservation perspective the Smiling Sand Eel is currently considered to be of Least Concern with stable, widely distributed populations. They are seldom seen by humans and are too rare to be of interest to most.