Yes he can and will eat a fire belly toad. They can get big enough to eat rats and small snakes. As for the harm him part it may because toads secrete stuff off of their skin that is supposed to make other animals not want to eat them. I would never suggest feeding your pac man frog a fire belly toad or keeping them in the same habitat considering fire belly toads are semi-aquatic and pac man frogs are a tropical frog. I hope this helps.
