Flathead Sea Catfish, Notarius planiceps

Flathead Sea Catfish, Notarius planiceps. Fish caught from coastal waters off Mazatlán, Sinaloa, April 2015. Length: 23 cm (9.0 inches). Catch, photograph, and identification courtesy of Kenneth Tse, Toronto, Canada.

Flathead Sea Catfish, Notarius planiceps. Fish caught from coastal waters off Puerto Chomes, Costa Rica, March 2021. Length: 26 cm (10 inches). Catch, photograph and identification courtesy of Eli (obsessiveangling.wordpress.com).

Flathead Sea Catfish, Notarius planiceps. Fish caught from coastal waters off Mazatlán, Sinaloa, October 2021. Length: 27 cm (11 inches). Catch, photograph and identification courtesy of Bart, The Netherlands  (worldangler.eu).

The Flathead Sea Catfish, Notarius planiceps, is a member of the Sea Catfish or Ariidae Family, that is also known as the Thick-lip Sea Catfish and in Mexico as bagre cabeza chata. Globally, there are fourteen species in the genus Notarius, of which three are found in Mexican waters, all three in the Pacific Ocean.

The Flathead Sea Catfish have the standard “catfish” appearance with a robust body. They are gray to bronzy green dorsally transitioning to white ventrally. Their fins are dusky. Their head is narrow and pointed, with medium sized eyes and a rounded mouth that has very thick lips and short upper barbels. Their anal fin has 18 to 22 rays; their caudal fin is deeply forked; their dorsal fin has 1 venomous spine and 7 rays and is followed by an adipose fin set far back on the body with a base that is similar to the dorsal fin base; and, their pectoral fins are finely serrated and have 1 venomous spine and 10 or 11 rays. They have 8 to 10 gill rakers on the first arch and 8 to 11 on the second arch. They do not have scales and their skin is smooth to the touch. Their lateral line is complete.

The Flathead Sea Catfish is a demersal species that is found in shallow turbid coastal waters and estuaries over sandy and muddy bottoms at depths up to 60 m (195 feet). They reach a maximum of 60 cm (18 inches) in length. They feed on small fish and a wide variety of benthic invertebrates including crabs, mollusks, and shrimp. The Flathead Sea Catfish 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 Flathead Sea Catfish is a resident of Mexican waters of the Pacific Ocean but is found only along the west coast of Baja from Magdalena Bay southward to Todos Santos, Baja California Sur, and along the coast of the mainland from Jalisco south to Guatemala.

The Flathead Sea Catfish is a straightforward identification and cannot be easily confused with any other species.

From a conservation perspective the Flathead Sea Catfish is currently considered to be of Least Concern with stable, widely distributed populations. They are an important commercial fish and are marketed fresh, frozen, dried or smoked. They can also be caught off the beach by recreational anglers. They are viewed as good table fare and have been a mainstay of subsistence fishermen for centuries. Caution: Care must be taken during handling to avoid being gaffed by the venomous spines found at the front of their first dorsal and pectoral fins which are often removed at the time of the catch.