[Peter Finke]

Ted is right. Male P. filamentosus are easily to be recognized by the constant form and colouration of the caudal fin alone. Your fish are round-tailed fish of the bintan-group; the reddish tinge in dorsal and caudal may indicate opallios (there are opallios presently in European countries available) but it is more likely that it is different a species. The colours are not as intense as they must be for a more exact determination because the fish are not yet accustomed to its new home. Only with very good photos a determination of fish belonging to the bintan-group may be possible.