You are over thinking it. I can't off hand think of anything you shouldn't use.
Just about anything frozen labeled something like 'seafood medley' or 'mixed seafood' will do just fine.
Shrimp, clams, mussels, scallops, raw fish, salmon, sqid, octopus, frozen or powdered cyclops, nori, just about any other frozen fish food you have on hand.
There are some specific recipes out there if you do a search, but when you read them, you'll likely see that you should 'feel free to substitute' with what you have on hand.
Once you make the leap, you need to feed sparingly at first as your fish get used to the new taste/texture.