I have 14 tiger barbs and they act like I never feed them, every time I feed them. They remind me of those old films of pirhanas eating! I feed them three times a day (a very small amount) and they always eat it all before it hits the substrate.
Your tank isn't cycled, so you really need to be careful about overfeeding in the meantime, otherwise you're just adding more ammonia to the amount being produced by the fish.
You ARE doing daily water changes, right?