Calubob, be careful with what you put in there, it will eventually get eaten. My bullfrog, Mija, has eaten goldfish, rosey red minnows, and just recently a CICHLID! I've never seen her actively hunting fish but they keep disappearing. I had two mbuna cichlids in her tank as a temporary home and only one is in in there now. I thought they would be safe because they were always hiding. Guess I was wrong.
I've tried big fish, small fish, fast fish, bottom feeders, top feeders, fish that hide, aggressive fish.....all have either evaporated or been eaten.
The only thing she hasn't touched yet has been my pleco's......so far. ; )
I've been having a snail issue since I've pulled the goldfish out, and now having trouble finding something to eat the snails, that won't get eaten by the frog. My only suggestion for you is really, really big fish or very inexpensive fish.
I am planning on rebuilding her tank and I'm thinking of building some sort of divider/split tank type of thing where she can't get to the fish, but that's a while down the road.
Please let me know what you end up doing, I'm always looking for what works