Yes, often at least. The species in which the sexes are most early to be distinguished is filamentosus followed by the true deissneri because of the colours in the unpaired fins. The extension of the caudal filament may begin to be visible with 1,5 cm, but sometimes the prolongation happens later. This is individually different. There are individuals who are fast and others who are late.
P. linkei is the least certain in this respect although its males filaments could become extremely long. They grow longer and longer (in some individuals and stocks) when the individuals are 2 cm or much more. The colours of the fins are in the sexes different, too, but not as obvious as in the other two.