Originally Posted by tanker
I'd say 10 gallons. Aunt Kymmie has a betta and some otos in a 6 gallon, I think, but you'd generally need plenty of room so they can keep out of each other's way. And, it would depend on the betta. Some bettas don't want "friends" no matter how big the tank....
Wow, good memory! Tanker is right, I had a 6gl with a betta and three otos. Some bettas don't care for tankmates. Always add the betta last, it'll be less likely to be territorial. I went with otos, but my tank was well established and HEAVILY planted. I'm not even sure the betta knew the otos were there. The Betta passed after 2 1/2 years, otos went to the 100g display and I set up the 6g as a RCS farm. The tank is now teeming with shrimp.