ADF are sorta blind, at least have a hard time seeing and my chomp at whatever they feel might be food.
Also people need to make sure there is food getting down to the
ADF as they are not going to get much of the Betta (or other tank inhabitants) eat most or all of the food.
Never have I heard or seen an
ADF go after a Betta. Obviously anything is possible.
But I am suspect about
ADF - African Dwarf Frog, being confused with an African Clawed Frog which would get SO MUCH Bigger, and could indeed attack a Betta. The frogs use a "if I can get it into my mouth it's food" policy. They sound so much alike and look similar when smaller.
So if you get some - better to get a few to be friends and pile on top of each other. Male is a more narrow body shape and female a bit more arrowhead/wider body shape.
And make sure to study pics of juvenile
ADF and ACF to make sure you are getting the right one, not depending upon a store employee to tell you. Also it is not unusual for
ADF to be a little bit fat. Often the skinny near bony ones seen in the store haven't been getting enough to eat.
The males make odd buzzing type noises as a mating call can check on you tube for examples if you are curious, and are adorable pets to keep.
Just make sure there are cliff, ledge type hiding places for the frogs to hide and escape out the back in case the Betta gets an aggressive streak.