I would initially say it was S. wui, also, but this link from Martin does confuse things.

I would like to see what it looks like from underneath and see if it has a broad head like S. wui. These maybe showing up as contaminants too, and were thought to be S. wui. Thanks, Martin!
However, to further confuse things,the S. wui I have or have had didn't always initially have any markings along the lateral area. Some have developed them over time.
The shape, especially the rubbery looking snout, looks like wui to me, but it may be another Sinogastromyzon species too. The color is a bit light though, maybe due to stress. If you did buy it, I would definately quarentine it for a bit. S. wui seem to show up occasionally in beaufortia shipments and are a nice find.
If you notice in the species index there is some variation in markings.
http://www.loaches.com/species_pages/si ... n_wui.html
As for keeping them, they are an interesting fish, similar to beaufortia in behaviour but a bit more reclusive. I have two now that I have had for 4-5 years and I have only seen them eat bloodworms. I even have one trained to eat out of the end of a feeding tube.