Fins are clear, and the dorsal waves like a knife-fish,but does not seem to have anything to do with motion. The oddball loach sketched by Martin is the ultra rare Vaillantella euepipterus, usually by catches from the kuhli loach fishery. They have an extremely forked tail and extremely long dorsal. In all my years of keeping loaches I've only come upon about 10 of these specimens. Presently I have five specimens.
Females develop the same long green ovaries as kuhlis do.
The biggest specimens I've seen were about 5-6 inches. The specimens pictured are about 4-5 inches and hail from Chantaburi Province, Thailand. Very secretive, they prefer hiding under the gravel or in crevices. The Thai fish is either a range extension or an undescribed species. Anyway, euepipterus has several dorsal bands preceding the fin, while maassi is described as being uniform brown.