I posted the info on Tiger Barbs in your other thread. They will be easier then Rummy Noses.
There are 3 species called Rummy Noses, I posted an article about them here.
Hemigrammus rhodostomus would be the easiest to try, using the same technique as the Tiger piece, but with lower Amazon water parameters.
The blackwater species really require difficult and water conditions, possible, but far from easy. Low pH, almost zero hardness, (thus totally unstable). They are also seasonal spawners, so you will need to replicate the Rio Negro tributary biome.