The Trinity is Trimurti in Hindi consisting of Brahma, the creator and Shiva, the destroyer with Lord Vishnu as the up-bringer. His fish avatar is known as Matsya-avtar in Hindu religious mythology.
Lord Vishnu so far has taken ten incarnations and they are known as Dashavatara which he needed to go for whenever the universe was in turmoil.
Every time each of Vishnu’s Avatars had the same purpose which he achieved by various means. Behind the avatars, the divine purpose was the restoration of Dharma or righteousness and also He came to earth for saving the planet and for protecting good people from the hands of the evil who were in form of demons like Daityas or Rakshasas.
Lord Vishnu’s first avatar was Matsya (Fish) Avatar, as per the Hinduism. During the great flood as mentioned in Hindu mythology texts like the Satapatha Brahmana, Lord Vishnu appeared as a Matsya to save the pious and the first man, Manu. Then he advised him to build a giant boat. Generally, Lord Matsya is represented as a four-armed figure with the lower of a fish and the upper torso of a man.
During the Satya Yuga, the people on earth had become irreligious and was living a disorderly life. This is when the heavens collectively decided to flood the earth and to get it prepared for the process of renovation. As the creator, Lord Brahma, was been given the responsibility to remodel the earth by Lord Vishnu. The responsibility came with the guidelines in the form of Vedas, the four principle books of Hinduism.
Lord Brahma thought of taking a rest for a while and then suddenly a horse-headed demon named Hayagriva came out of Brahma’s nose and he cunningly stole the Vedas from him. Fleeing from there Hayagriva hid himself deep in the oceans of the earth.
During that period a pious king named Satyavrata worshiping Lord Vishnu regularly wished to meet Him. This made Lord Vishnu to decide to pay a visit to Manu.
The pre-ancient Dravida king, Satyavrat was a devotee of Lord Vishnu, who later came to know as Manu. Manu one day was washing his hands in a river then suddenly a little fish swam into his palm. She pleaded with him to save its life. Manu put it in a jar, but soon it outgrew. Manu then moved the fish into a tank, then in a river and then finally in the ocean but to no avail. The fish kept outgrowing.
Then Manu figured it out that it is not a normal fish. Holding his both hands he bowed down before the fish. Then revealing herself to be Vishnu, God told him that a deluge would occur within the next 7 days that would destroy world and all life.
The fish said, ‘Manu, listen to me carefully, at the end of Kaliyug, a mare living at the bottom of the ocean, will open her mouth for releasing a poisonous fire. The fire then will burn the whole universe, even Gods, constellations along with everything. Then the seven clouds of doomsday would flood the earth until everywhere everything will look like a single ocean. Therefore, Manu, I ask you to build an ark to take “all the varieties of seeds, all medicinal herbs, being accompanied by the seven saints” and do not also forget to give shelter to the serpent Vasuki and other animals.
When arrived the time and with the flood approaching, Manu’s ark was ready. Then with the flood sweeping over the land, Manu asked Lord Vishnu, ‘O Lord, why mankind has to meet such a deadly fate?’
Replying to it, Lord Vishnu in the Matsya avatar, said, ”Manu you are the only moral man alive and it is you only whou would be the father of the future generations of men.”
The huge Matsya then killed demon Hayagriva and returned the Vedas back to Brahma. Coming back to Manu, the Matsya tied himself to Manu’s ark where the serpent Vasuki was being used as a rope. Thus Matsya protected them from the storm and the floods. Finally when the water subsided and the storms ended, the Matsya left Manu and the others at the Himalayas. Lord Vishnu got back to His abode and Manu started then the human civilization again.
