SB 8.24.58
sa tu satyavrato raja
jñana-vijñana-samyutah
visnoh prasadat kalpe ’sminn
asid vaivasvato manuh
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
King Satyavrata was illuminated with all Vedic knowledge by the mercy of Lord Visnu, and in this period he has now taken birth as Vaivasvata Manu, the son of the sun-god.
Purport by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
Srila Visvanatha Cakravarti Thakura gives his verdict that Satyavrata appeared in the Caksusa-manvantara. When the Caksusa-manvantara ended, the period of Vaivasvata Manu began. By the grace of Lord Visnu, Satyavrata received instructions from the second fish incarnation and was thus enlightened in all spiritual knowledge.