Sooty Sand Eel, Bascanichthys bascanoides
The Sooty Sand Eel, Bascanichthys bascanoides, whose common Spanish name is tieso manchitas, is a species in the Snake Eel or Ophichthidae Family, known collectively as tiesos in Mexico. Globally, there are seventeen species in the genus Bascanichthys, five of which are found in Mexican waters, two in the Atlantic and three in the Pacific.
The Sooty Sand Eels have elongated slender cylindrical bodies with a rounded cross section. They are red-brown dorsally fading to white-yellow ventrally. There is a prominent pale streak along the entire base of their dorsal fin. Their head has a short blunt snout with small eyes and one row of small conical teeth. They have a prominent front nostril tubular on the tip of their lower jaw behind the base of their front nostril. Their anal and dorsal fins are low and the origin of their dorsal fin is midway between their gill openings and eyes. Their caudal fin is hard, pointed, and finless. Their pectoral fins are small consisting of narrow skin flaps of similar length and width. Their tail is equal to or greater than 50% of total length.
The Sooty Sand Eels are found mostly within burrows in sandy and muddy bottoms at depths up to 70 feet. They reach a maximum length of 100 cm (39 inches), as established by the fish photographed below. This is an exceedingly rare species and very little is known about their behavioral patterns.
In Mexican waters the Sooty Sand Eeel have a limited distribution being found only along the west coast of Baja from Magdalena Bay southward along the southwest coast of Baja and in the Sea of Cortez as far north as Kino Bay, with the fish photographed below documenting a northerly range extension for this species.
The Sooty Sand Eel is difficult to identify and is quite similar in appearance to the Panamic Sand Eel, Bascanichthys panamensis and the Round Sand Eel, Bascanichthys cyclindricus, both of which have tails that are less than 50% of total length.
The Sooty Sand Eels are exceedingly rare and of limited interest to most.
Sooty Sand Eel, Bascanichthys bascanoides. Fish provided by the commercial fishermen of Bahía Kino, Sonora, March 2015. Length: 100 cm (39 inches); Tail 55%. Photo courtesy of Maria Johnson, Prescott College Kino Bay Center, Kino Bay, Sonora. Identification courtesy of H.J. Walker, Jr., Scripps Institution of Oceanography.