These are the commonly available invertebrates and non-fish that are available for freshwater tanks. It's general info. (None are going to work with your stock IMO except snails.)
Shrimp and snails are the prime, non-fish candidates. Both are easy to feed, and will eat leftovers and algae. (your frogs would probably eat the shrimp though)
Dwarf Frogs can work in many freshwater setups (not clawed frogs though), although they can be difficult to feed. They tend to be much slower than fish.
Mollusks (whatever type) are very difficult to feed. Most starve to death rather quickly. They need small food items/microfauna that are not commonly found in the aquarium.
Crayfish (freshwater lobsters) tend to be predatory/opportunist.
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Now for saltwater aquariums, there are a host of invertebrates and non-fish that are acceptable.
