Well, I don't think you could call any of them "universal". There is no food that would be good for a clown loach, lionfish, gourami, python, iguana, monitor, cat, dig, hamster, sugar glider, love bird, and a macaw. That said, there are certainly foods that can transfer between species. Monitors and tegus can eat pretty much anything, including feeder fish and crawfish, moist cat food, ground turkey, insects, rodents.
As for rodent diets, they will certainly eat meat, but most rodents, at least domestic mice, Mus musculus, and domesticated rats, Rattus norvegicus, do much better and live a longer healthier life on a prominently grain based diet. And before anyone asks, yes, this makes them much healthier feeder animals.
As for feeder fish, they can be feed to monitors, certain snakes, like garters, banded & ringed water snakes, (though this is mostly necessary in wild caught animals), false water cobras. I suppose you could feed them to certain cats. I wouldn't. One of the main problems with feeding fish to things that aren't other fish, is parasites. Especially feeder goldfish, which are typically raised in extremely cramped, not necessarily "clean" tanks. I have told many people, if you are going to feed a reptile allot of live feeder fish, you should learn allot about Panacur. How to dose it, how to administer it to your particular animal. So I would avoid it with cats as well.
