A candiru, Paracanthopoma sp. (Siluriformes: Trichomycteridae), associated with a thorny catfish, Doras phlyzakion (Siluriformes: Doradidae), in a tributary of the middle Rio Negro, Brazilian Amazon

Amazonian vampire catfish, known regionally as “candiru”, are recognized as hematophagous fishes, but information on their ecology remains limited. We provide the first report of Paracanthopoma sp. (Vandelliinae) found attached to the body surface of a thorny catfish, Doras phlyzakion Sabaj Pérez et Birindelli, 2008, bellow the lateral bony plates, rather than at the gills where they have usually been found. The specimens had not recently ingested blood or other identifiable fish remains (flesh, skin, or mucus), which could be an indication they have been using this host for protection or as a phoretic association, rather than for feeding. Thus, the interaction of vampire fish with the host catfish may be more complex than previously understood.