Baryancistrus demantoides is a species of armored catfish endemic to Venezuela.It reaches a length of 15.1 centimetres (5.9 in) SL.It lives around granite rocks in flowing water, in the upper parts of Orinoco River. The colour is green-brown with yellow spots on the head and parts of the body. The dorsal fin is connected to the adipose fin, a feature that distinguishes this species from the rest of the Ancistrini, except Baryancistrus niveatus, Parancistrus and Spectracanthicus.