Matsya
Matsya (Fish) is the first avatar of Vishnu in the Dashavatara. In Shatapatha Brahmana, a fish saves Manu from the great flood; later Puranas identify it as Vishnu. Matsya warns Manu, has him build a boat, tows it to Himalayas with Vedas, sages, seeds. In Bhagavata Purana, slays demon Hayagriva who stole the Vedas. Depicted as giant golden fish or half-Vishnu/half-fish. Embodies flood myth motif.