Hello Dany and welcome to FF! Right now would just let frog be in the 10 gal. with 50-50 set-up. I would not feed it until tail is almost or totally gone. Do 50-100% water changes with dechlorinated water daily depending on volume unless the is a filter with cycled media in the water section. I'm guessing a water depth around frog height or slightly more will allow frog to swim in it fine.

Even if American Bullfrog, you might be able to keep in 55G for a while. If other smaller species; then you can re-evaluate once ID is made. Good luck !