Just thought I'd post a few pictures of some of my FEMALE betta's in a 20 gallon tank fighting Viciously,
By the time the fight was finished We had some pretty beat up females, Some ended up dying!
So don't be fooled thinking Females are docile or don't fight as viciously as males do...
I had Females even turn and end up killing some males...
The pictures really don't show you the half of the fight, These two kept Biting each other and ripping finage badly, They'd take a break then go right back at it, They ultimately had to be separated as they would not stop!
They swam around the tank many times locked in a bite, and came out tearing fitting to kill each other, If another crossed their path they ripped into them too. Oft times had all six going at it at the same time...
and Red females are much worse!
So don't be fooled thinking any two Betta's will be compatible,