Hare Krishna,
Once, at the end of the previous kalpa, a demon named Hayagrīva wanted to take the Vedic knowledge away from Lord Brahmā at the time of annihilation. Therefore the Supreme Personality of Godhead took the incarnation of a fish at the beginning of the period of Svāyambhuva Manu and saved the Vedas. During the reign of Cākṣuṣa Manu there was a king named Satyavrata, who was a great pious ruler. To save him, the Lord appeared as the fish incarnation for a second time. King Satyavrata later became the son of the sun-god and was known as Śrāddhadeva. He was established as Manu by the Supreme Personality of Godhead.
Replies
Once, at the end of the previous kalpa, a demon named Hayagrīva wanted to take the Vedic knowledge away from Lord Brahmā at the time of annihilation. Therefore the Supreme Personality of Godhead took the incarnation of a fish at the beginning of the period of Svāyambhuva Manu and saved the Vedas. During the reign of Cākṣuṣa Manu there was a king named Satyavrata, who was a great pious ruler. To save him, the Lord appeared as the fish incarnation for a second time. King Satyavrata later became the son of the sun-god and was known as Śrāddhadeva. He was established as Manu by the Supreme Personality of Godhead.
https://www.vedabase.com/en/sb/8/24
Hope it helps.
Hare Krishna.