I had stocked my sorority with 9 beautiful betta ladies. Luckily, only 1 torn fin through the process. I read 8 to 10 bettas for a 20G long. I decided to go with 10. However, My last betta that I ordered showed up with a free extra betta from seller. Nice of him but not part of the plans. That makes 11 instead of my planned 10. I know fish can’t count but will they be ok? So far, with exception of some periodic chasing off, everyone seems fine. They all eat together peacefully. Opinions, please.