Manu, the first human, found a small fish in his washwater. The fish begged protection from the larger fishes, in return for which it would save Manu from a flood. Manu kept the fish safe until it grew large, and later the fish saved Manu from a deluge. [Kelsen, in Dundes] "The Lord of the Universe," to preserve king Satyavarata from dangers of the depravity of the age, sent him a large ship, and told him to gather himself, medicinal herbs, and pairs of brute animals aboard it to save them from a flood. Seven days later, the three worlds were flooded and darkened. The god appeared in the ocean as an enormous fish, a million leagues long, and Satyavarata tied the ark to its horn. [Howey]
or
Howey, M. Oldfield. The Encircled Serpent, Arthur Richmond Company, New York, 1955.