Hmm, interesting fish! My best guess, though not the correct one would be Schistura kohagenesis (not correct spelling). Although that is not exactly the correct identification thats what these photos remind me of.
Going by "Fishes of Laos" that first fish looks very much like Schistura xhatensis, "Freshwater Fishes of Central Vietnam" has a fish with similar looking markings on it called Schistura thanho but that has a red tail.