The 2001 Niarcos Expedition to Venezuela was a joint project of the American Museum of Natural History and the Institute of Tropical Zoology of the Central University of Venezuela (UCV). A joint expedition was conducted from 28 February to 19 March, 2001 to the Río Cuao, Amazonas State, Venezuela. The expedition team comprised 10 persons, led by Dr. Schaefer (AMNH) and Prof. F. Provenzano (UCV), accompanied by Dr. Jonathan N. Baskin (California State Polytechnic University Pomona), plus one field technician and 6 field assistants. A total of 4001 specimens of 86 species of fishes were collected from 12 localities in the middle to lower Río Cuao, representing the largest and most comprehensive collection of freshwater fishes from the Río Cuao assembled to-date. Included among the fish species collected were new and undescribed species of trichomycterid catfishes found living within the sand on the bottom of shallow river margins, several new characids from a variety of habitats, and several new loricariid catfishes from rock crevices in fast-flowing rapids. Specimens have been divided between AMNH and MBUCV.