Ageneiosus inermis, also known as Fidalgo, Dawala or Mandubé, is a species of driftwood catfish of the family Auchenipteridae. It can be found throughout South America, from Colombia and Venezuela to Uruguay and northern Argentina.
The name Ageneiosus marmoratus has been recently synonymized with A. inermis. The description was based on a strongly pigmented juvenile of A. inermis. The species feeds on a piscivorous diet, mainly hunting catfishes in the family Loricariidae and Doradidae.