Definition of upside-down catfish in English:

upside-down catfish

noun

  • A small freshwater catfish that habitually swims upside down so as to browse on algae on the undersides of floating leaves. Native to central Congo, it is popular in aquaria.

    Synodontis nigriventris, family Mochokidae

    • ‘This fish is seen far less often in the aquarium trade, but also appears under the name of upside-down catfish.’