Smallest tank to house Male betta and Neon Tetras?

[Jessicatm137]

You'd need at LEAST a 10 gallon, 15 gallons is a lot better.

[Olympia]

I'd do 15 gallons, just for the sake of being able to have 10ish neons as opposed to 6, it will reduced their aggression towards the betta significantly (because they will pick on each other).

[Bombalurina]

I wouldn't try it until you know what your water parameters are.