Paired fish with human faces in folk art - Corresponding with paper-cut "Yin-yang fish" and "Baby with coiled hair," "Paired fish with human face" on painted pottery symbolizes the first ancestor, god of the universe. Looking at this image, god has one eye open (from the human face on painted pottery unearthed at Jiang Village), and the other eye closed (from the human face on painted pottery unearthed at Banpo). Apparently, they are not the natural but conceptual eyes. With god of the universe, the open eye is the sun, the day
and yang; the closed eye is the moon, the night, and yin. 
It is common practice in Chinese folk art to liken eye to the sun and the moon. in folk art painting created by the wives in northern Shaanxi, all human faces are round-eyed, same as the eyes of the tiger. Their eye balls are always in the center of the white nsheltered by eye lids. It is believed that a closed eye is the moon and an open eye is the sun. Therefore, eyes should be painted bright and shining. To me, that might also be a cultural comprehension from the primitive clans.