Hi gravybrain,
Schistura pridii are very sought after and usually very hard to find. They usually command a
very high price tag. If you have a mature aquarium set up as a 'River style' with plenty of flow and oxygenation, they would be worth going back for. Here is our profile:
http://www.loaches.com/species-index/schistura-pridii
Schistura sp. 'Giant' could be one of hundreds of fish from the
Schistura genus, so you'd need to provide photographs of these for an ID.
If the
Botia histrionica really were 6", that is a very good size and would be considered pretty much fully grown. 5" is a more usual size for these fish.
The
B. kubotai are also of good size, but do grow to 5" or so.
The main thing to consider though, is whether these fish are in good health.
Lazer loach must be a made-up common name, one which I must say I haven't personally come across before. Can you describe these fish or provide photographs?
With regards to large
Botia, which species are you wanting to know more about? There are several species which get quite large, not all of which are friendly.
Emma