I added my Betta to my 20 gallon Neon tank, and he immediately started chasing them and I found one dead several hours later. I removed him, but even after he was out of the tank it was just a domino effect and I lost Neon after Neon and had to
euthanize some of them. I lost 8 when all was said and done over about a week period, long after the Betta was removed. So, with my experience, no it doesn't work and not a good idea. Everyone I asked told me so and I listened to the one person who said they'd be fine and found out the hard way for myself.