Sorority Stocking?

Hey all, long time no see!

I'm thinking of setting up a sorority tank but I'm unsure as to how many girls I should get, I currently have 5 in my community that'll be moved over but looking to get more. Tank is either going to be 60L or 90L, looking more like the 90L at the moment though. So my question is, how many girls could I put in a 60L, and how many girls could I put in a 90l? When I start this project I'll be sure to keep you all updated with lots of pictures!

90l would be a great sorority tank - room for other fish too if you wanted, maybe some cories or bristlenose plec. In a 90l you could have quite a few - maybe 10, possibly a few more depending on filtration and how planted your tank is. Lots of plants and decor will help break up the tank space into smaller territories for each girlie, and will break the line of sight so the girls should bicker less.

I had 6-7 in a 60l, but I think more space is better, plus the more girls you have the better they will all get along

I would go for the 90L because the more space the better. I had 9 in a 110L and they just beat each other up none stop so i got rid of the lot.
In a 90L you also have you also have room for other fish. Maybe go for a asia biotope and go for
8 female bettas
10 harlequin rasbora
15 Kuhli Loach

I'd definately go for the bigger tank! I had 8 female betta in a well filtered 54L tank and they all seemed to get along fine and had lots of hiding places etc, but they looked so crowded. I upgraded their tank to 128L and they have lots of plants of different sized, bogwood with caves and arches, coconut caves etc. There's 10 females in there now plus 5 six week old guppies (who will now probably grow up thinking they're bettas as they copy EVERYTHING the females do and try and follow them around all day) and it's a really peaceful sorority.
The best thing about getting a bigger tank for a sorority is if you ever see a female you just have to have, you know you've got the room for her, unlike male bettas LOL. And as the other have said, you can put other fish in there too, bigger tanks are way more versitile for spontanious LFS fish-buying :-D