It would be very rare occurance for a betta and any danio to get along well at all. All known danio are schooling fish also, so they prefer to be in groups of 5-6 or more. Bettas would do fine with Kuhlia loaches, in my opinion. (we have a 55g with both of those in it and have not had a problem for the 6 months or more they've been together.) Kuhli loaches do prefer groups, but it is not as detrimental to their health to not have the groups, as it is with schooling fish. I would describe Kuhli loaches as sociable semi-pack fish. They tend to hang out together at some times, but also wander off on their own a lot.
Good luck, and let us know how it goes.
