Is it possible to have frogs with fantails in a tank? Or will they just eat them?

I'd forego the frogs. First of all ,there are two types.The African Dwarf Frog(ADF) which like tropical temps and stay pretty small,and then there are the African Clawed frogs,whose bodies alone get to be the size of your fist-not counting their arms & legs. ADF's will get eaten by your goldies if they can fit them into their mouths.The filtration is normally more than the frogs can actually handle too.The Clawed frogs get to be a nice size. They will actually eat your Goldies if they can fit them into their mouths. The bigger they get,the more aggressive they are.I once saw a tank of these at my LFS,and was shocked at how many had full sized frogs,the same size as theirselves---in their mouths! They swallowed them whole! Nah,I'd personally keep the ADF's in a tropical tank,or better yet---single specimen tanks.