Betta fish community. I have 5 girls in 3 gal tank and they are fine - dont fight and look beautiful. 1st I had 3, one got sick and died. I bought a new one. 3 lived together for couple months - no fights. 2 weeks ago I added 2 girls. Everybody is alive and friendly. So I dont know. I also have a boy in a separate tank. He is a year old.