The nijsseni male has a very beautiful red seam in the tail, which is else light blue.
I have several times considered buying the nijsseni, but hesitated to do it since it is difficult to breed.
Now I have bought it anyway, mostly because I wanted some small colorful fish, but also because I have realized that you cannot expect to be able to breed every species you own. Restraints on time and space is very much something to be reckoned with in the aquatic hobby.