Nemacheilus ruppelli, also known as the mongoose loach is a species of fish in the genus Nemacheilus. This fish is endemic to the Western Ghats of India. Recent evidence shows that there is only a marginal raw mitochondrial genetic distance between Nemachilichthys shimogensis and N. ruppelli.[1] Although morphometric difference occur at the population level, Keskar et al. conclude that there are no significant differences separating the two species.[1] Therefore they treat N. shimogensis as a synonym of N. ruppelli. The Eschmeyer's Catalog of Fishes follows this treatment.[2]
Nevertheless, Nemachilichthys shimogensis is listed as a separate species by the IUCN and Fishbase to this day.[3] [4]
N. ruppelli is presently reported from the Krishna River system in the Western Ghats, India. Specimen where found in the following rivers: Thunga, Mula-Mutha, Krishna River, Indrayani, Hiranyakeshi, Nira River and Koyna.[1]
N. ruppelli lives in moderate to fast-flowing rivers, usually on the bed. N. ruppelli prefers mud, small rocks, silt and pebbles. It frequently occurs in association with submerged roots of riparian plants and aquatic vegetation.[1]