Pardon me for being skeptical.
1. "Researchers have found..."
Comment: Why not a specific name of a person or at least the name of an institution. Science teachers have been known to call themselves scientists. I'm not surprise anyone call themselves a researchers.
2. "scientists write in a journal published by the UK's Royal Society. "
Comment: 2nd hand anecdotal.
3. On the BBC website, When you attempt to enlarge the image of the fish, they show you a smaller fish on an irrelevantly over sized finger.
4. Does it look like a fish ?
Seems more like something picked out of the nose.
5. Instead of photographing it on the finger, why isn't it placed in a container? There is either something fishy about it or it is cruel.
If they want to photography a dead fish, is it not possible to show it's magnified with full feature? And it is hard to place it beside a mm scale of a ruler?
6. It says "Science may have discovered Paedocypris just in time - but many of their miniature relatives may already have been wiped out"
Comment: This claim of many "miniature relatives" being wiped out, seems to be pure imagination.
7. I'm sure if they might be threatened more by a lost of their habitat than by humans. Given their ability to survive in small pools of water, it should be no problem re-populating it else where.
Why all the big fuss? I'd say there is an agenda to save the habitat rather than the fish. If it does exists at all.
More evidence is needed.
Edited to add:
This is not meant to question anyone's sensibility, just cannot help to note the "flaw".
But then again ...

To be skeptical or not to be skeptical... That is the question.