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 Home : Botia sidthimunkis vs Botia cf. nigrolineatas


From: Kamphol Udomritthiruj (bo@thai.com)
March 8th, 2000

Six years ago, at the suggestion of ichthylogist Tyson Roberts, a friend and I went on an expedition to a watershed stream and village called Nam Wa in Nan Province, Northeastern Thailand. It was December and there in knee length cold water we observed flashes of what we thought were an undiscovered population of B. sidthimunki. With no seines, we asked the local villagers to catch some of the loaches for us. Incredibly, the villagers hand caught the loaches, trapping them under stones. And thus started a seasonal (winter) fishery that has continued until now of these "sidthimunkis". It became obvious, that these were not sidthimunkis on three counts. One was the consistently strong horizontal lateral stripe that is exhibited by the majority of these loaches from Nan at all sizes (1 - 4 inches). Second, the original type specimens of sidthimunki and the sidthimunkis prior to the fishery of the Nan giants 6 years ago, sidthimunkis never grew beyond 2 - 2.5 inches. They grew fat and gravid, and I've seen them as old as 10 yrs old, but they were always dwarf botias. Third, the original sidthimunkis come from Kanchanaburi Province from the Kwai River system in Western Thailand. Dams on the river system have caused their rumored extinction in the wild. All true sidthimunkis in the trade today come from a single commercial breeding (induced breeding) operation and that is why they are rare in the trade.

The Nan giants are breeders that come upstream during the dry season (winter) to breed. As I write this, the sizes of these loaches will have reduced significantly and in the next 2 - 3 weeks, shipments to the US will be of smaller sizes (2 inches) which are caught further downstream.

The loaches from Nan also match the zoogeography in the distribution of B. nigrolineata which is described from the Mekong River system. Without scientific verification, these are at best Botia cf nigrolineata. They are however, definitely not sidthimunki on account of pattern, size, if not distribution. The Nan loaches are also much more difficult to keep in terms of keeping their body weight on. When freshly caught, the have proportionately small heads compared to their round full bodies and thick tails. In captivity, they slowly thin out and their heads become disproportionately larger than their body depth. It is a matter of high metabolism for these loaches which live in cool and fast flowing waters.

And to answer Mike Ophir's question, yes, after examining my preserved specimens of Nan Botia cf. nigrolineata, there is a fourth pair of vestigial barbells on the chin, a mere pair of stumps.

The jpegs below show comparisons of full grown Kanchanaburi "true" Botia sidthimunkis and Nan Botia cf. nigrolineatas, at 1.5 inches, at 2 inches and from the top, showing consistent differences in their dorsal striping.

Kamphol Udomritthiruj

(Click to enlarge)

From: Anuratana Tejavej (opsarius@hotmail.com)
Date: April 9th, 2000

Here are some low quality pictures of Botia sp. cf. nigrolineata to complement the comparison between it and the dwarf loach. The 1st picture is one of the more extensively patterned Nan loaches. The 2nd picture is one of the fuller body Nan loach. The 3rd picture is the "lineup" to compare the size and pattern differences between the "large" dwarf loach in the foreground and the around 3 1/2 inch Nan loach in the background.

Photo by Anuratana Tejavej. All Rights Reserved


Photo by Anuratana Tejavej. All Rights Reserved


Photo by Anuratana Tejavej. All Rights Reserved

From: Graeme Robson (lr002a8789@blueyonder.co.uk)
Date: October 13th, 2003

From: David Rinaldo
Date: March 25th, 2002

Botia sidthimunki

Click for full-sized image


Botia nigrolineata

Click for full-sized image


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