I'm not sure (I can't see details of mouth and belly) but it seems that you have young Spatuloricaria, but without more details like their origin, and important morphological features, I can't be absolutly affirmative for the ID. Nevertheless, I can tell you that they are not R. teffeana.
Thanks Raph - that certianly seems more like them
I will try to get some better closeup photos - these were just quick snaps! But sometimes that's easier said than done.
Ps: sorry for posting in the wrong section - I didn't realise there was an ID section!