I know the rules of Betta sororities is a minimum of 5 females.
I have had these 3 for 7 days now and have not seen any aggression, Remember these 3 were introduced to each other as young fish and have been living in a 5 gallon cube for at least 4 months before I got them, and they came from a sorority tank in a pet shop when the people I got them from got them.
Please watch this video then tell me why I should mess with this dynamic by adding more fish.
This is how they spend their day there is virtually no chasing no flaring or body slapping.
Sorry for bad video.
I do not need any more plants .
Each tank and fish do differ a lot and no two tank being the same can make suggestions hit or miss at times.
Just as no two fish's personality are the same, especially so with bettas.
You are the only one who can judge whether its suitable to add more female bettas into your tank to help spread the agression but if there is no trouble with your 3 then thats certainly perfectly acceptable.
No one here is saying you should definitely add more female bettas to bring numbers up to at least 5, they are given as a suggestion in case aggression and problems occur.
Also the same goes for adding more plants, in some cases this help, again, with the aggression factor to break lines of sights and to provide hiding spaces. This is certainly not the case with your lush tank.
Bettas, being not a shoaling nor a schooling specie absolutley differs on a case by case basis since they are usually a solitary specie who makes a mockery of the usual fishkeeping rules
This thread will certainly help those who may be considering setting up a betta or a sorority tank
EDIT - I see Eagles posted at the same time