Bundahishn 18

On the nature of the tree they call Gôkard' it says in revelation, that it was the first day when the tree they call Gôkard grew in the deep mud within the wide-formed ocean; and it is necessary as a producer of the renovation of the universe, for they prepare its immortality therefrom.

The evil spirit has formed therein, among those which enter as opponents, a lizard as an opponent in that deep water, so that it may injure the Hôm.

And for keeping away that lizard, Aûharmazd has created there ten Kar fish which, at all times, continually circle around the Hôm, so that the head of one of those fish is continually towards the lizard.

And together with the lizard those fish are spiritually fed, that is, no food is necessary for them; and till the renovation of the universe they remain in contention.

There are places where that fish is written of as 'the Ariz' of the water;' as it says that the greatest of the creatures of Aûharmazd is that fish, and the greatest of those proceeding from the evil spirit is that lizard; with the jaws of their bodies, moreover, they snap in two whatever of the creatures of both spirits has entered between them, except that one fish which is the Vâs of Pankâsadvarân. 6.. This, too, is said, that those fish are so serpent-like in that deep water, they know the scratch (mâlisn) of a needle's point by which the water shall increase, or by which it is diminishing.

Regarding the Vâs of Pankâsadvarân it is declared that it moves within the wide-formed ocean, and its length is as much as what a man, while in a swift race, will walk from dawn till when the sun goes down; so much that it does not itself move the length of the whole of its great body.

This, too, is said, that the creatures of the waters live also specially under its guardianship.

The tree of many seeds has grown amid the wide-formed ocean, and in its seed are all plants; some say it is the proper-curing, some the energeticcuring, some the all-curing.

Between these trees of such kinds is formed the mountain with cavities, 9999 thousand myriads in number, each myriad being ten thousand.

Unto that mountain is given the protection of the waters, so that water streams forth from there, in the rivulet channels, to the land of the seven regions, as the source of all the sea-water in the land of the seven regions is from there.