These fishes are undoubtedly interesting, but it is not possible to determinate them at present. The information of the the trade (“south-east Asia”) is of no use.
Therefore I want to suggest how to get along: In similar cases – import by the trade without reliable informations on locations and no clear identification as a described species – we have named the fish with the trader’s name and the year. For example: We once had a very nice stock that was imported by a German wholesaler named “Mimbon aquaristics”: it appeared in the German trade in 1998. The fish resembled the species that was later named P. alfredi. But at the time of that import this species was not yet scientifically described (that happened in 2005 only). Today, we are pretty sure that spec. Mimbon 98″ was an alfredi-variant; maybe the true and strict P: alfredi. However, since we did never get any exact information on the location where it had been caught wen cannot be more exact.
So, I suggest that this fish should not been provisionally named “spec. rubrimontis/tweedie/opallios” but “spec. name of the trader and 2015”. Additionally, we shall know that this fish resembles to a certain extent tweediei or phoenicurus or even opallios. But there is no name type “aff. tweedei/phoenicurus/opallios”. This is knowledge but not a type of provisional name.
David, since you informed us about this interesting fish and we cannot be sure that it is a hitherto already described species (I do not think that there could be new species from western Malaysia, but possible from vast Kalimantan and Sumatra) you should tell us the provisional name follwing that type of naming: importer/trader and year (I think: 2015).
Then we wait how the young fish develop. They should be kept separately and bred separately. Maybe a new import delivers more information. If not, we must possibly live with that provisional name for a long time, perhaps forever.