Help starting a betta sorority?

Hello I needed help on setting up a betta sorority. I ve had a female betta for about 2 years and yesterday I went into Petco and was convinced into buying two young bettas to start a sorority. Since then the two fish have been getting along but one is not eating and is on the bottom of the tank. I wanted to know... show more Hello I needed help on setting up a betta sorority. I ve had a female betta for about 2 years and yesterday I went into Petco and was convinced into buying two young bettas to start a sorority. Since then the two fish have been getting along but one is not eating and is on the bottom of the tank. I wanted to know if I should put her in a separated tank to grow(she is the smallest) or just wait it out... possibly get another?
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