Lefua is a genus of small loaches native to cool, temperate East Asia, with atlas records from Japan, China, Russia, Mongolia, and both Koreas — a range that reaches further north than most loach genera, into habitats with genuinely cold winters. They are usually grouped with the stone loaches, elongate bottom-dwelling fish with a downturned, barbel-fringed mouth for sifting mud and gravel, and the atlas's seven species run a modest 2.5–4 in. Several, including the rice loach (L. costata) and the hotoke loach (L. echigonia), favor slow, vegetated water — rice paddies, ditches, ponds, and quiet stream margins — rather than the fast rocky riffles many other loaches prefer.
Lefua sees only limited aquarium interest, mostly among specialist loach and cold-water-biotope keepers rather than the general trade; their tolerance of cool temperatures and still water makes them an option for unheated setups, but detailed husbandry information stays thin outside dedicated fishkeeping circles. Conservation status leans favorable where assessed — four of the atlas's seven species rank Least Concern — though two are Not Evaluated and one Data Deficient, so a full picture of the genus's wild status is still incomplete.