Overview
Matsya (Sanskrit: मत्स्य, meaning 'fish') is the fish avatar of the Hindu god Vishnu. He is often described as the first among Vishnu's ten primary avatars (Dashavatara). According to tradition, Matsya rescued the first man, Manu, from a great deluge, ensuring the continuity of life and the lineage of humankind.
In iconography, Matsya may be depicted as a giant fish, frequently golden in colour, or in an anthropomorphic form with the torso of Vishnu joined to the rear half of a fish. This dual representation reflects the avatar's role as a bridge between the divine and the natural world.
The earliest known account of Matsya appears in the Shatapatha Brahmana, where the fish-saviour is not associated with any particular deity. In the post-Vedic period, the figure of the fish-saviour came to be identified with Brahma, and subsequently with Vishnu, with whom Matsya is now firmly associated in later Hindu tradition. The legends linked to Matsya expand and vary across Hindu texts, accumulating new themes over time.
The narratives carry layered symbolism. In one well-known version, a small fish placed under Manu's protection grows progressively larger, eventually revealing itself as a divine being who guides Manu through the flood. Manu is thus regarded in tradition as the progenitor of the next race of mankind. In later versions of the legend, Matsya slays a demon named Hayagriva, who had stolen the Vedas, and is therefore lauded as the saviour of the scriptures. The tale is associated with the wider motif of flood myths, which is found across many cultures of the world.
References
Adapted from the English Wikipedia article on Matsya.