Years ago I kept Bettas, in a backyard pond outside over the Summer and indoors during the indoor season here in zone 6b. I moved them into a 30 gallon tank, ( that is what I had on hand) with lots and lots of Anacharis/ plants to hide in. I may have used a small bubbler/sponge filter in a corner. The Bettas were quite happy in this arrangement and spawned/built bubble nests in the corners. ( that's when I shut the bubbler off) Interestingly enough, in this environment I was able to keep several males, females and subsequent fry in the same tank without them killing each other, since there were enough hiding places and they were used to each other. I did try to have a ratio of at least 1:3 male to female fish.
