Why did you get the frog if you had no accomodations for it?
I don't know anything about piccaro frogs (in fact I have never even heard of them) so I cannot comment on husbandry, but regardless, two animals in an enclosure should always be approximately the same size, even if the animals do not have cannabilistic tendancies, they can still present other problems such as bullying. Its never a good idea to mix different species unless they are from the exact same geographic location, and are in an enclosure sizeable enough that they would never have to see eachother, say in a room-sized enclosure. Animals have their own host specific bacteria, which can be harmful to other animals. Not to mention that even if you were to house any two animals together, you cannot introduce them for months, since all newcomers must be quarantined for a decided period of time from all established animals.
Whenever in doubt, DON'T. If you were uncertain of the situation, you should just set the frog up in a temporary container. Tupperwares are fine for that.