Hi Stephan,
Yes it is very difficult to ID Paros, it can be frustrating when exporters rarely identify the fish correctly.
I have spent a few hours looking at numerous papers and images on the internet and have come no closer to an ID. I have found some similar species and was looking at the similarities between my fish and P. tweedei, alfredi and phoenicurus. I almost thought they might be phoenicurus, but not sure how the caudal fin differs on younger fish? Also the Raffles biology paper says phoenicurus should have a black filament on ventral fins, whereas mine are blueish.
I think the blue in the fins also rules out tweedei, but not 100% sure of this. It most looks like some images of alfredi that are on the seriouslyfish website, but I was led to believe by importer that mine came from Sumatra, so that also seems unlikely.
Rod