Dark or black vertical line on nail beds 19 year old african american i tend to bite my nails a lot too.my aunt has the same thing.should i worry?????

Melanonychia.: The most common diagnosis is melanonychia which is benign hyperpigmentation of the nailbed in persons with dark skin color, and is a normal variant. But just to be safe, you should have a doctor examine your fingers to make sure there are no suspicious signs of melanoma. It's unlikely, but it's necessary to make sure since we can only give general advice in this section.