FusionDex.org

Eating rotted matter increases the potency of the poison gas that Munchfing emits. Because of this, Munchfing tries to wait until its food rots, but it often can't control itself and ends up eating the food while it's still fresh.

Getting up close to a POKENAME will give you a chance to observe, through its thin skin, the toxic gases swirling inside. It wolfs down its weight in food once a day, swallowing food whole with almost no chewing.