I have a black spot in the middle of one of my eyes? what is cause g that?

Many causes: You need to have this checked because there are many possible causes of this. A new floater is a common cause, but the floater would tend to move around and not be exactly in the center of the vision. All other causes are mostly involving the retina, so a dilated eye exam by an ophthalmologist is indicated. Even if it just a floater, the dilated exam is indicated to rule out a retinal tear.