The frog won't hurt your fish while they're sleeping. There's a chance he could eat them if they'll fit in his mouth, but that has to be a pretty small fish. Also if you have larger fish, you'd have to worry about them eating your ADF.
With a tank your size I would be worried about the height. ADF's need to get to the surface to breath. If it's a young frog, he may tired out before he can get there.
Feeding an ADF in a community tank can also be a problem. They're not quick to find the food and the fish may get the food first.
Don't reply on fish food. ADF's have their own nutritional needs.
Frog & Tadpoles pellets along with frozen bloods worms is a good diet for him.
Here's some info about
African Dwarf Frog Care
ADF's are a lot of fun, but personally, I enjoy them in a species only tank. I've heard that they might work with a betta depending on the size tank. If this is your 10g, there's a chance it might work.
Have fun with yours and good luck
