well first off, i don't think getting a female necessarily removes the fighting out of the equation. i have plenty of female cichlids that put up a big fight and are very nasty towards their tankmates.
back to your question - if you feed them good stuff (e.g. new life spectrum, hikari, kens, frozen foods) and change the water on a very frequent basis (i do ~30-50% water changes on my grow out fish once every 4-5 days), there shouldn't be any reason not to see 1" per month. i am actually moving onto the new life spectrum wagon because i have recently started using their foods and i have definitely noticed that the fish are much more receptive to it and they genuinely love it. if my haitiensis and frontosas are doing well on it, i don't see why other less 'picky' fish won't thrive on it as well. just my two cents.
