How many for a 20g sorority?

[Briggan]

Hi!
Currently, I have 7 lovely bettas in my 20 gallon fem betta sorority. I’m looking to add a nerite snail, but not that’s not an immediate concern. Since I’m pretty much addicted to bettas at this point, would it be bad if I added two more for a total of 9 bettas in a 20 gallon?
There hasn’t been any aggression for the month I’ve had them, and the tank is decorated with many plants and hiding spots.
Thanks!

 

[FishGuest5123]

Is it a 20G long? I had 11 in a 20long.

 

[Briggan]

It isn’t a long, it’s a tall until I can switch to a standard or long.