Well, here's some updated pictures now that the Indian Crimson Loaches have been in for a month and a half. Many have now got much more subdued colours, although there are still a few really bright specimens. Having had more time to observe these, I must say that they have become very, very aggressive towards one another.
A brightly coloured specimen (male?)

A beautiful lighter coloured specimen (female?)

Isn't this loach just the cutest?

Close-up (difficult to get completely in focus, these loaches are very small!)

Overhead shot, again not completely sharp, but shows the markings on the back quite nicely:


And finally here is this rather 'evil' looking chap:

I think this is a different species.

Emma