Well here are the main fish I like the most, all are labeled "Peaceful." The pH levels are within reach of them all including the needs of the Betta. Also they all fall into the area of the water temp needed for Bettas. Also they largest they get is the Badis which is 3" so they are around the same sizes. Do you think these could all coexist with female Bettas? Tank is a 30 gallon which will be planted, and is filtered by a Marineland Penguin 200, can get a larger or add another filter if needed. Also currently houses 5 females, who are now all getting happily along with each other.
Neon Blue Dwarf Gourami
Ghost (Glass) Shrimp