Congo Tetras are an underrated species IMO, when they are young the males don't show their "Rainbow" of colors, when they become sexually mature their color is amazing, Defiantly worth having in a community aquarium.
Males are easily distinguishable , their caudal fin looks raggy like it has been fin nipped by another fish.
Water conditions should be the same as most community species:
pH - 7
GH - 50-75ppm
Temp - 23-26c
Dark Substrate also helps.