Panama Sand Eel, Bascanichthys panamensis

Panama Sand Eel, Bascanichthys panamensis. Underwater photographs taken in Zihuantanejo Bay, Guerrero, February 2026. Photographs courtesy of Ron Woheau, Zihuantanejo. Productive discussions with Dr. Benjamin Victor, Coralreeffish.com noted and greatly appreciated.

The Panama Sand Eel, Bascanichthys panamensis, is a member of the Snake Eel or Ophichthidae Family, and is known in Mexico as tieso de Panamá. Globally, there are seventeen species in the Bascanichthys Genus, of which five are found in Mexican waters, two in the Atlantic and three in the Pacific Ocean.

The Panama Sand Eel has an elongated slender cylindrical body. They are light brown dorsally transitioning to tan ventrally with a whitish dorsal fin. Their head is whitish with brown markings and the lateral pores are white. They have a relatively short snout with the mouth equipped with small conical teeth set in one row on the jaws and two rows on the roof of the mouth and a crescent shaped gill cover. The anal and dorsal fins are set low on the body with the dorsal fin origin being on the head before the gill openings. Their pectoral fins a small flap behind the gill openings. They have a relatively short tail that is 43 to 49% of total length which has a hard finless tip.

The Panama Sand Eel is a demersal species that is found within sandy substrate and within estuaries and mangroves at depths up to 30 m (100 feet). They reach a maximum of 76 cm (2 feet 6 inches) in length. They feed on mobile invertebrates. The Panama Sand Eel is an exceedingly rare species and is poorly studied with very limited information available about their lifestyle and behavioral patterns including specific details on age, diet, growth, habitat, longevity, movement patterns, and reproduction.

The Panama Sand Eel is a resident of Mexican waters of the Pacific but has a limited distribution being found in an isolated population from La Paz to Santa Rosalia, Baja California Sur, long the east coast of the Baja Peninsula and along the west coast of the mainland south of Mazatlán, Sinaloa.

The Panama Sand Eel, is difficult to identify and is quite similar in appearance to the Round Sand Eel, Bascanichthys cylindricus (prominent nostil extending from the upper jaw; subtle white stripes on the head).

From a conservation perspective the Panama Sand Eel, is currently considered to be of Least Concern with stable, widely distributed populations, however, their long-term viability is currently threatened via coastal development and mangrove removal. They are exceedingly rare, seldom seen by humans, and of limited interest to most.