Please follow Brian's suggestions. As a rule of thumb, you'd almost never different frog and toad species together. I would even go as far as not to house more than one individual per tank. One reason is that the bigger one will eat the smaller one if they're house in the same habitat. Most amphibians are not discriminate eaters as they will eat whatever that fits in their mouths. And two, like Brian said, amphibians are likely toxic so if they eat each other they will all ended up dying. Three, housing multiple amphibians may risk disease transmission, especially with wild caught animals. If you had previously kept amphibian in your tank, I would suggest to decontaminate before you put a new animal in it by rinsing it with diluted bleach (in a ratio of 1 part bleach per 10 parts water).