Welcome to the forum, Liz. Have you read the fire-bellied toad article? I think it covers most of the basics in there. The words "frog" and "toad" mean next to nothing. All toads are frogs. The word toad is just an English term used to describe wartier and/or drier looking frogs. From a scientific naming point of view, fire-bellied toads are not even in the same family of frogs as what we call "true frogs", nor are they in the same family as what we call "true toads".

It sounds like you have a massive aquarium for two small toads. I would consider downsizing. Also keep in mind that the toads do not require lighting. The lights are for your viewing pleasure and the benefit of the plants.

As for food alternatives, Crickets are a good staple food, provided you dust them with vitamin/mineral powder occasionally, and/or you gutload them with a commercial cricket diet. There aren't that many cricket-sized alternative foods for fire-bellied toads but there are suggestions in the fire-bellied toad care article (linked at the left and in the top menu of every page on this site).