It is uncertain what exactly the Fauna of Mirrors look like, but what is known is that they do not resemble creatures of the earth in any way. They became hostile to humanity after a brutal war between the two worlds and a humiliating punishment imposed on them by Huang-Di, the Yellow Emperor of early Chinese legend. They are connected to any mirrors and reflective surfaces, sharing a close bond with fish and other sea creatures. The Fish, in some versions of the tale a leader of the creatures, is a shimmering animal visible deep in mirrors that is impossible to catch.
A long time ago, mirrors contained an alternate world inhabited by living creatures different from the animals of the earth. Beings were able to cross between the two worlds through mirrors during an unspecified period of peace.
However, the mirror people eventually invaded the earth, causing much destruction and havoc before Huang-Di, the legendary Yellow Emperor, was able to restrain them. He used his magic to trap them in their own mirrors and took away their own shapes and their powers, forcing them to take on the shape and actions of the victorious earth people.
The Yellow Emperor's spell was powerful and enduring, but not permanent. One day, it is said, ominous things will begin to happen: a line of a color never before seen will appear in the mirror, unearthly creatures will begin to stir, the clatter of weapons will be heard. The first creature to regain its power will either be the Fish of the Mirror or the Tiger of the Mirror. The legend ominously adds that in the second conflict the mirror people will be aided by the water creatures, and the alliance will this time triumph.
- The plot of the novel The Chinese Mirror by Alice Major involves an ancient mirror slowly releasing the mirror people, led by the Tiger of the Mirror. The goal of the protagonists is to re-seal the boundary between the worlds.
- The anthology Looking for Jake by China Miéville contains a short story called "The Tain". It is set in a post-apocalyptic future London in which the world has been conquered by the Fish of the Mirror and imago vampires from the mirror world. A few surviving humans continue to resist.
The Fish is a shifting and shining creature that nobody has ever caught but that many say they have glimpsed in the depths of mirrors. According to Herbert Allen Giles, belief in the Fish is part of a larger myth that goes back to the times of the Yellow Emperor. In those days the world of mirrors and the world of men were not, as they are now, cut off from each other. They were, besides, quite different; neither beings nor colors nor shapes were the same. Both kingdoms lived in harmony; you could come and go through mirrors.
One night the mirror people invaded the earth. Their power was great, but at the end of bloody warfare the magic arts of the Yellow Emperor prevailed. He repulsed the invaders, imprisoned them in their mirrors, and forced on them the task of repeating, as though in a kind of dream, all the actions of men. He stripped them of their power and of their forms and reduced them to mere reflections. Nonetheless, a day will come when the spell will be shaken off. The first to awaken will be the Fish.
Deep in the mirror we will perceive a very faint line and the color of this line will be like no other color. Later on, other shapes will begin to stir. Little by little they will differ from us; little by little they will not imitate us. They will break through the barriers of glass or metal. Side by side with these mirror creatures, the creatures of water will join the battle. And this time, they will not be defeated.
In Yunnan they do not speak of the Fish but of the Tiger of the Mirror. Others believe that in advance of the invasion we will hear from the depths of mirrors the clatter of weapons.
- Jorge Luis Borges, "The Fauna of Mirrors", from The Book of Imaginary Beings