[mike61289]

Purple firefish don't tolerate conspecifics (unless already a mated pair) or other species of firefish very much. They will induce stress on others to the point of constant harassment or jumping.

I have to agree with jmm overall though. You will eventually be left with a single individual, maybe a pair.

Make sure your aquarium is completely covered as they are small and will find the tiniest of escape routes.