As discussed here, Bhagavan took on the form of a fish at the time of deluge after the lapse of the Chakshusha Manvanatara, the one before the present. For the purpose of propagating the Vedas in the present Manvantara, he accepts the role of an Acharya and teaches King Satyavrata the import of the Vedas (next verse mentioning even Purana, Sankhya and Yoga (like karma yoga)):
इत्युक्तवन्तं नृपतिं भगवानादिपूरुष:। मत्स्यरूपी महाम्भोधौ विहरंस्तत्त्वमब्रवीत्॥
When Satyavrata had thus prayed to the Supreme Personality of Godhead, who had assumed the form of a fish, the Lord, while moving in the water of inundation, explained to him the Absolute Truth.
However, this puranic lore seems to be in apparent contradiction with the Bhagavad Gita wherein Bhagavan says that the knowledge was passed to Manu through Vivasvan i.e. the sun deity:
इमं विवस्वते योगं प्रोक्तवानहमव्ययम्। विवस्वान् मनवे प्राह मनुरिक्ष्वाकवेऽब्रवीत्॥
I taught this imperishable Yoga to Vivasvan; Vivasvan taught it to Manu; Manu declared it to Iksvaku
- Srimad Bhagavadgita 4.1
As can be seen, the puranic lore states that knowledge was passed on directly from Bhagavan to Satyavrata (who becomes Manu), but the Gita places Vivasvan between the two.
One one hand, the Matsya avatara is famous for happening to give Manu knowledge to propagate in the current Manvantara. If we say that the Gita is correct, an entire story and purana (concept of Matsya purana, not the one available today) would have to be negated. It is to be remembered that there is no puranic story of Bhagavan giving any knowledge to the sun deity Vivasvan
On the other hand, the Gita verse too cannot said to be wrong as it has been quoted by many acharyas.
How do we solve this contradiction?