Genidens barbus, the white sea catfish or marine catfish, is a species of catfish in the family Ariidae. It was described by Bernard Germain de Lacépède in 1803, originally under the genus Pimelodus. It is an oceanodromous species that is found between the mouth of Negro River in Patagonia and eastern Brazil. It reaches a maximum total length of 120 cm. It has been recorded spawning between the months of August–December. The maximum known life expectancy is 36 years.

It is preyed by the South American sea lion. The fish is valued as food in Brazil.