I have two Bumble Bee catfish and a Crown tail betta. The FBT's have eaten any guppies or small fish. They are predators, afterall.

Betta's are very hearty and if you have a filter, their water temp range is the exact same as a FBT. No need for heaters. Things is, my betta eats crickets. So, if you feed your toads in the tank, get small ones and put in extra because "swimmers" may not make it to become toad food, if you get me. But, it's great fun to watch. The betta waits under the rocks and lily pads and when the crickets crawl underneath, he picks them off one by one. So, you will need a few extra. However, in the days in between, they will eat dried blood worms.

The catfish are nocturnal for the most part and swim around in the rocks down below when the frogs are quietly sleeping. They cleanup the poo from the betta too, which is great. They eat shrimp pellets, 2 each every other day. Don't overfed them, the water will get icky. But, they don't bother the betta or the toads.

I would strongly recommend against any goldfish or guppies or any other fish in that family or feeder fish. They are just plain disgusting...not much better I can say about them. They make the water cloudy and messy, the filter will be more clogged with their mess than the toads, they carry parasites and ICK and other diseases. The toads will be in danger, quite honestly. It's something alot of people do, but in my humble opinion, it's a bad practice all together.

Good luck.