Srimad Bhagavatam — Ashtama Skandha, Shloka 9
Matsya-avatāra: The Lord as Fish Saves the Vedas and Guides Satyavrata
ज्ञात्वा तद् दानवेन्द्रस्य हयग्रीवस्य चेष्टितम् । दधार शफरीरूपं भगवान् हरिरीश्वर: ॥ ९ ॥
jñātvā tad dānavendrasya hayagrīvasya ceṣṭitam dadhāra śapharī-rūpaṁ bhagavān harir īśvaraḥ
大いなる魔王ハヤグリーヴァの企てを悟り、万徳円満なる至上主ハリは魚（マツヤ）の姿を現し、ヴェーダを護るためその阿修羅を討ち滅ぼされた。
Because everything was inundated by water, to save the Vedas it was necessary for the Lord to assume the form of a fish.
FAQs
In this verse, Śukadeva explains that the Supreme Lord Hari assumed the fish form after understanding the plans of the Daitya king Hayagrīva—showing the Lord’s timely descent to protect dharma.
Because He discerned Hayagrīva’s intentions and actions; as the supreme controller, He adopted an appropriate form to counter the threat and accomplish His divine purpose.
When challenges arise, this verse reminds devotees that the Lord is aware of all circumstances and can provide protection and guidance in the most suitable way—encouraging faith, steadiness, and dharmic action.