Limatulichthys is a genus of whiptail catfish (family Loricariidae, subfamily Loricariinae) with a wide range across northern and western South America, and the atlas records it from Venezuela, Brazil, Colombia, Guyana, and Peru — spanning both Orinoco and Amazon basin drainages. Whiptails carry the loricariid armor plating and sucking mouth but in a slender, elongated body plan built for lying flat against submerged wood and leaf litter rather than clinging to rock faces. Atlas species run notably large for whiptails, from about 15 to nearly 9.5 in as adults.
The sandpaper whiptail catfish, Limatulichthys griseus, is the genus's main presence in the aquarium hobby — a peaceful, algae- and biofilm-grazing bottom dweller valued by loricariid keepers for its unusual elongated shape and camouflage patterning, best kept over driftwood and leaf litter it can rest against. L. nasarcus is far less documented. Conservation status is only partly resolved (L. griseus Least Concern, L. nasarcus Data Deficient), and like most loricariids, breeding in the aquarium is uncommon and not well documented for this genus.