Definition - What does Matsya mean?
Matsya is the Sanskrit word for "fish" and also refers to the first of the incarnations of the Hindu god, Vishnu. As Matsya, Vishnu is said to have saved the world and the first human (Manu) from a great flood. As a deity, Matsya is typically depicted as a large fish or half human with a fish bottom.
In yoga, matsyasana is a pose also known as fish pose. In this pose, the yogi assumes a prone position facing skyward then the back arches, raising the chest up and dropping the head back so that the top of the head rests on the ground.
Yogapedia explains Matsya
In Hindu mythology, Manu survives the great flood by seeking refuge on an ark, which Matsya guides to safety. Some versions have Matsya saving the Seven Sages who accompanied Manu on the ark. In other versions of the tale, the Vedas are hidden by a demon and Matsya kills the demon to recover the sacred texts and rescue Manu and the sages.
Matsyasana is so-called because the body is resembles the shape of a fish. The posture is believed to connect the yogi to the balance of water and earth, with the chest representing a wave and the body grounded to the earth. The asana is part of the primary series of Ashtanga yoga and is commonly performed in Hatha yoga as well.
Traditionally, matsyasana is associated with activating the visuddha (throat) chakra, which is associated with wisdom and self-expression.