This story is about incarnation of first vishnu “Matsya Avatara”. In this incarnation, Lord Vishnu saved this world from the terrible deluge. Once before Kalpant, a very big demon stole the Vedas from Brahma ji by deceit. Then the darkness of ignorance spread all around and sin and unrighteousness continued to dominate. Then Lord Vishnu took the form of a fish to protect Dharma and killed that demon and protected the Vedas.