Nemachilichthys is a small genus of stone loaches in the family Nemacheilidae, restricted to fast-flowing streams and hill rivers in India. Like other nemacheilid loaches, its species are slender, elongate, and scaleless or nearly so, with a flattened head and underslung mouth adapted for foraging over gravel and stone substrate in clear, well-oxygenated water. The atlas covers 2 species - Nemachilichthys ruppelli, the mongoose loach, and N. shimogensis, the Shimoga loach - both modest in size at roughly 3–3.5 in.
Neither species is a mainstream aquarium fish; loaches in this genus turn up only occasionally in the specialist trade and are otherwise of mostly regional, scientific interest as part of India's freshwater biodiversity. Where care is attempted, the expectation from related nemacheilids is a cool, fast-flowing, well-oxygenated setup with a sand or fine gravel bottom rather than a standard community tank. Conservation status is only partly resolved: one species is assessed as Least Concern, while the other has not yet been evaluated.