jñÄtvÄ tad dÄnavendrasya
hayagrÄ«vasya ceá¹£á¹itam
dadhÄra Å›apharÄ«-rÅ«paá¹
bhagavÄn harir īśvaraḥ
jñÄtvÄ - after understanding; tat - that; dÄnava-indrasya - of the great demon; hayagrÄ«vasya - of HayagrÄ«va; ceá¹£á¹itam - activity; dadhÄra - accepted; Å›apharÄ«-rÅ«pam - the form of a fish; bhagavÄn - the Supreme Personality of Godhead; hariḥ - the Lord; īśvaraḥ - the supreme controller.
Because everything was inundated by water, to save the Vedas it was necessary for the Lord to assume the form of a fish.