Sandy Ridgefin Eel, Callechelys cliffi

Sandy Ridgefin Eel, Callechelys cliffi. Underwater photograph taken in Zihuantanejo Bay, Guerrero, April 2026. Photographs and identifications courtesy of Ron Woheau, Zihuantanejo.  Identification courtesy of Dr. Benjamin Victor, Coralreeffish.com.

The Sandy Ridgefin Eel, Callechelys cliffi, is a member of the Snake Eel or Ophichthidae Family, and is known in Mexico as tieso vela aquillado, tieso aquillado arenero and tieso vela punteado. Globally, there are fourteen species in the Callechelys Genus, of which five are found in Mexican waters, three in the Pacific Ocean and two in the Pacific Ocean.

The Sandy Ridgefin Eel have a creamy white head and a yellowish body and are covered with numerous fine spots that are less than their eye diameter. The dorsal fin has a distinct white margin. They have moderately elongated body with a compressed head and body. Their head is short with an overhanging mouth, and their snout is long and pointed with a medium groove on the underside that extends to before the nostrils. The rear nostril is in the lower lip under the eye and is covered by a flap. The teeth are small and set in one row on the jaws. Their caudal fin ends in a hard finless point. Their dorsal fin is high and originates on the head just behind the eye and extends to the tail tip. They lack pectoral fins. Their lateral line extends from the head to the tail.

The Sandy Ridgefin Eel is a demersal species that is a burrowing fish that spends the majority of their time half submerged within rocky and sandy substrate with only their heads exposed at depths up to 30 m (100 feet). They reach a maximum of 46 cm (18 inches) in length. They feed on invertebrates and small fish. Their ability to retreat into the sand and their spotted pattern provide camouflage to help them avoid predation. The Sandy Ridgefin Eel 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 Sandy Ridgefin Eel is a resident of Mexican waters of the Pacific Ocean but have a limited, fragmented, poorly documented distribution being found from Loreto to Cabo San Lucas along the east coast of Baja California Sur and along the coast of the mainland in the greater Mazatlán area. The photograph above documents the presence of this species in Guerrero.

The Sandy Ridgefin Eel can be confused with the Blunt-toothed Snake Eel, Pisodonophis daspilotus (gray color with anal and dorsal fins with yellowish margins) and the Pacific Sailfin-eel, Paraletharchus pacificus (dark body with transitions to white ventrally).

From a conservation perspective the Sandy Ridgefin Eel is currently considered to be Data Deficient. They are seldom seen by humans and are too rare to be of interest to most. Their long-time viability is treated by habitat loss due to human development.