can someone please give me an idea whats going on w/ my fish? i noticed today the eye is not as vibrant black but it still is. w/ these tetras, they have like a gold ring w/ the black pupil. the ring around the eye is not as bright gold as it was. and right above the eye; its nose, is dark also. its only on one side of its face. it's swimming around like its fine but never seen this. i'm wondering if its an injury or a disease?