Saddleback Sculpin, Oligocottus rimensis

Saddleback Sculpin, Oligocottus rimensis. Underwater photograph taken within Mission Bay, March 2020. Photograph and identification courtesy of Bob Hillis, Ivins, Utah.

The Saddleback Sculpin, Oligocottus rimensis, is a member of the Sculpin or Cottidae Family, and is known in Mexico as charrasco ensillado. There are five species in the genus Oligocottus, of which three are found in Mexican waters of the Pacific Ocean.

The Saddleback Sculpin has an elongated slender body. They are mottled in color with various shades of red and green dorsally transitioning to tan and green ventrally. They are difficult to detect in their native environments as their blotchy camouflage coloration matches its surroundings. Their head has a preopercular spine with one point, which is a key to a correct identification. Their anal fin has 13 to 15 rays; their caudal fin is slightly rounded; their dorsal fin has 8 to 10 spines and 16 to 19 rays; their pectoral fins have 13 to 15 rays; and, their pelvic fins have 1 spine and 3 rays. They have 5 or 6 gill rakers. They are covered with small scales.

The Saddleback Sculpin is found in rocky substrates in the intertidal zone and in kelp beds and eel grass to depths up to 21 m (70 feet). They are small in stature reaching a maximum of 6.4 cm (2.5 inches) in length. They consume amphipods and polychaete worms with older larger fish also consuming crabs and shrimp. In turn they are preyed upon by a wide variety of fishes. They have the ability to breathe air and can survive out of water for extended periods of time. They are also known to move if their location becomes inhospitable. The Saddleback Sculpin 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 Saddleback Sculpin is a resident of Mexican waters of the Pacific Ocean but has a limited distribution being found from Guerrero Negro, Baja California northward along the central and northwest coasts of Baja.

The Saddleback Sculpin is a straightforward identification and cannot be easily confused with any other Sculpin found in Mexican waters.

From a conservation perspective the Saddleback Sculpin has not been formally evaluated. They are relatively small in stature and of limited interest to most.