I've kept schools of white clouds with my bettas. They don't seem to mind each other and white clouds aren't fin nippers. In my experience, the white clouds can handle temperatures in the 70s, but rosy red minnows cannot.
100g Native Fish Pond, 55g Goldfish/Catfish Community, 50g Plant Pond, 40gB Tetra/Cory Community, 20gHM Community, 20gH Turtle (Bender [RES]), 20gL Turtle (Kif [YBS]), 15g Reef, 5.5g Betta (Okami), 5gFBH Betta (Pron), 5gHex Betta (Twister)
2 dogs, 13 cats, 2 turtles, 1 bearded dragon and 1 crested gecko