isn`t there a golden rule? i mean, with guppys it`s customary to put 3 females for every male. i started with 4 male, 2 were killed. then i got 2 females. 1 died and now i see the males fighting...
I haven't noticed any real difference in aggression between my male and female dwarf cajuns. In my experience, they don't attempt to mate unless the female is in season. After she's fertilized, she'll go and hide and protect her eggs.
The rule for guppies is usually to keep the males from harassing the females to death. I have 6 male guppies in a 5g tank and I've never witnessed them attacking each other.