i have kept peacocks & mbuna in a much smaller tank without issues, in fact the peacock was the more aggro one. you have a big tank which is a great size, i would say you will be fine with the current stocking numbers although there may be some issues when the giraffes get big but they may not be as well. I have kept a similar number of africans in a much smaller tank so as long as your filtration is adequate then i think it should be fine. just watch it as time goes on & see how it pans out.