That's just for Demasoni. That's supposedly because they are territorial and are prone to pick on fish that look like them (which includes their own kind). Having more gives more to pick on to disperse the aggressive nature.
btw, I think the gap looks fine.
KJ
Demasoni:
"First and foremost, a minimum of twelve should be kept in any size tank to help disperse aggression. This not only keeps a single male from being dominant over all others, it helps females and sub-dominant males from being chased to exhaustion (and death) by getting "lost in the crowd". A small group of 5 or 6 simply will not work, as the dominant male will systematically kill off each tank mate until only he remains. Male to female ratio is unimportant when they're kept in groups of this size, which is a bonus, because accurately determining their gender can be a futile task. It's very important not to house these fish with similarly colored species (e.g., Cynotilapia afra or Metrialclima lombardoi). "
[URL="http/www.cichlid-forum.com/articles/p_demasoni.php"]http/www.cichlid-forum.com/articles/p_demasoni.php[/URL]