|Here is a series of pictures from an article in Icthyol. Explorer July 1998, page 98.
The upper picture was listed as a 34.6mm specimen, 142b is 49.1mm and the bottom is 71.1mm. The fish can be found in Upper Xe Bangfai, Mekong basin in Laos, Yunnan and Thailand. Found in riffles, in clear, fast flowing water.
So according to this reference the young fish has no vertical bar to make a chained pattern but as the fish grows they develop the bars. The article says the B. nigrolineata is a subspecies of the sidthimunki and reported to be from Thailand. The difference noted is the amount of vertical bars, the sidthimunki has 5-8 bars and the nigrolineata has 8-10. Also the midlateral strip is narrower in the nigrolineata. The sidthimunki develops it chain pattern at a young age and small size 20mm where the nigrolineata seems to develop it around 50mm.
The article also claims the sidthimunki only reaches 40mm(>1.5 in) in natural conditions.
Here is my e-mail address so fell free to comment.