your males with that limited space will fight as soon a a female becomes ripe. nyereri when housed closly also have a tendancy to beat up females. i would rotate the males and keep the extra in a community tank you may have or a 10 gallon. and switch them out every month or so. adding some dithers may help keep down male female aggression. this is my expierance with the 7 species of nyereri i have kept.