Originally Posted by ThePearlFish
I have "Jumbo" Neon Tetras with my Betta, but I think It totally depends on the Betta's personality and space and so forth as said above. I purposefully got the Jumbo variety of the neons, cus I figured if they are a tad bigger the Betta might not see them as much of a snack, and my tetras all adore my Betta and follow him around like he's some kinda king. But I got lucky. It's all up to the Betta.
The jumbo neons are called Cardinals ;) I kept them in my 55 planted. Betta's and neons are a mixed bag, some times it works, some times it does not.
As mentioned you will either get neons nipping betta fins, betta killing neons, or all goes fine.