Your tank looks beautiful! The Betta in the second picture look exactly like my female Betta "Karma"!
A word of warning though... I had tried keeping 5 female Bettas in a well planted tank and they got along for about 5 days and then started trying to kill each other. Keep a close eye on their behaviour. They may need to be separated. We on the Betta board have had no success with keeping females together. They do eventually start fighting and killing each other. Also, Bettas are not good with Gouramis and Tiger Barbs. Gouramis come from the same family of fish as Bettas so they may get aggressive and have been known to kill or be killed by Bettas. This may apply more to males but I'm be very careful.
Thanks for the advise. I will keep a close watch. These bettas were very small when introduced into this tank. They grew up together with the gouramis. I have 2 females and 2 male betta in this tank along with 2 Golden gouramis and 6 Tiger barbs. All of them were introduced very young and have grown up. So far, I haven't had any problem. Hope, I wouldn't have one in future. Anyhow, as suggested by you, I will keep a closer watch.
I'm very worried about your male Bettas. You should never keep two males together, no matter how young or even if they were raised together. They will kill each other for sure. They will also fight with the gouramI and possibly kill it when the Betta gets bigger. The tiger barbs will eat the tails of the males when they get bigger. I would recommend you at least take the males out and put them in separate tanks alone. Male Bettas don't really get along with many fish and should be in 5+ gallon tanks alone or with peaceful fish like Cory catfish or Otos etc.