Ernstichthys is a genus of banjo catfish in family Aspredinidae, found in Amazon and Orinoco basin streams across Ecuador, Brazil, Peru, and Venezuela. Like other banjo catfish, Ernstichthys species have a flattened, guitar-shaped body — a broad, depressed head tapering to a slender tail — an adaptation for lying still and camouflaged against sand or leaf-litter substrate. The four atlas species are small, 1–2.5 in, consistent with the modest size typical of banjo catfish genera outside the larger Aspredo and Bunocephalus lineages.
The dwarf banjo catfish (Ernstichthys megistus) is the only species in the genus with an English common name in the atlas; Ernstichthys as a whole is a genus of mostly scientific interest, occasionally reaching specialist importers but never a mainstream aquarium fish, in keeping with the general obscurity of banjo catfish beyond the handful of species that do turn up in the trade. Conservation data are thin: three of the four atlas species have not yet been formally assessed, and the fourth is Data Deficient — unsurprising for small, cryptic, substrate-dwelling catfish that are inherently hard to survey.