At this spot I could see three distinct species of fish. Sorry such a terrible photo. These fish were dark in colour, and possibly 9-10cm long? The water was fast flowing. Further below them I could see a larger lighter coloured fish.
Hi DougT, thanks for your information. In my naivety I thought three different species due to the difference in size and colour. I looked up this species and found that they grow to 13.5cm, so all could be in this size range. I would still have been thrown by the apparent different colour, the mid-sized fish appearing quite dark. I have added two cropped new photos from the same day, one showing the mid-sized fish more clearly, and the last one showing the larger fish on the left of the picture, all added for more information, not to dispute your id. Thanks again for the identification, I will now know what they are when I see them :)