I am in agreement here. I don't think its a good idea to feed frogs to frogs. Its expensive and potentially dangerous. Frogs (and amphibians in general) use toxins to protect themselves from predation, so they really don't make good feeder items. Of course they have their own predators that can over come this, hognose snakes, Heterodon sp. come to mind. A North American bullfrog, Lithobates catesbeianus (I assume that's what we are talking about) could probably eat a wide variety of frogs species, but why take a chance. If you are thinking of feeding smaller bullfrogs to a larger one, forget it. That's a great way to pass diseases on to your frog.

There was a study I read about in National Geographic a few years back, where they fed various salamanders to tiger salamanders, Ambystoma tigrinum. One of the salamanders used as a feeding item were smaller tiger salamanders. They were fed both sick and healthy salamanders. Those that ate salamanders of an unrelated species were fine regardless if the prey animals were healthy or sick. Those that ate the sick tigers, became ill themselves. Something to think about.

As far as feeding your bullfrog, stick to crickets, mealworms, waxworms, superworms, earthworms, horn worms, roaches, silkworms, and so on. Its a much healthier and risk free diet.