I haven't come across any specific ratio figures for this species, so I see nothing wrong with what you have. In most cases, females outnumbering males is solely for the benefit of the females, as they will not be driven as hard if there are fewer males than females. This doesn't matter with all species of shoaling fish of course.
Sparring between males is why we keep them in groups, as it is natural behaviour and we hope to see it as it is one sign of happy fish. As long as it doesn't become so aggressive that the fish get hacked to pieces.
Which is rather unlikely with this species.