After the loss of my African Clawed frog Flipper, I would like to get into frog keeping again. Unfortunately, I've had to downsize to a 10 gallon that contains a single platy. I have read that dwarf frogs and S. tropicalis reach very similar sizes, but only S. tropicalis is a danger to fish. If both frogs will eat anything that fits in their mouth and are the same size, why are dwarf frogs considered safe to keep with fish while S. tropicalis is not?