Matsya = Fish.
Asana = Steady Pose.
This posture will help to open the chest cavity, increase range of movement in the shoulders, chest and upper back and it is also known for helping to balancing the endocrine system.
How to Perform Matsyasana
Begin lying on your back, lift your chest a little to place your hands palm down under your buttocks, lift your chest up and release the top of your head to the ground. Join the insides of your legs and point your toes.
If your head does not touch the floor, do not worry just look up, feel that you are opening your chest as you breathe slowly.
Remain in this posture for thirty or more complete breaths through your nose.