I have a 10 gallon that was divided in 1/2 with a betta and Corys catfish on both sides(I like having a bottom feeder in all my tanks. Iused to have 2 but are down to one now).
One of the Corys died awhile back and last week, one of my bettas got sick. I took out the Betta and kept him in my small tank for his final days and removed the barrier.
Although I would love to save more Bettas, the barrier was a algae magnet and I decided to give one betta free run of the place.
I got a second Cory and also got 2 danio zebras. Its been a week and all are getting along fine. Ive spent hours watching them and they havent bothered the betta and vice vera.
However Bettas do have personalities and all are different. My betta that just died hated snails and would always kill them, this one doesnt mind them.
Becuase the other fish are always zooming around I give the Betta lots of places to chill - 2 caves and plenty of plants to hang out in if he wants to get away from the smaller crazier fish for awhile.
But everything has been great so far. Danios and Corys are dull in color and the Betta doesnt even bother with them. Ive even seen the Corys resting with the Bettas on occassion.
Ive had Corys with Bettas for years, the Danios is a first time for me. The Betta that just died would occassionally chase the Corys if the Cory annoyed him, but he never hurt him. they shared a tank for almost a year.Im tempted to get one more small fish but Im still keeping a eye on these guys.
All Bettas are different,but if u have a mellow calm Betta, danios and corys should be fine. If hes aggressive, he should prob be alone.