Fish pose or matsayasana is one of the poses my yoga teacher calls "a chest opener." Chest opener sounds like "can opener." A simple kitchen staple.
Below is a grainy still of one of the famous fathers of American yoga, B.K.S. Iyengar, doing matsyasana (according to some ancient texts, "the destroyer of all diseases.") See how his upper back makes a U?
Because I have thoracic and cervical osteoarthritis, the pose is more literally like a can opener, like the scene from Alien when the alien pops out of John Hurt's chest. My chest is like Middle Ages armor. A slab of 200-year-old oak, or a coral reef. Fixed.
However, I love fish pose.
I do it with an assortment of assistive devices, blocks and bolsters and straps and I lie there lifting my sternum a bit to the overhead lights, steaming with effort, trying not to be blind with jealousy of the vertebrae of the other people in the room, the healthy middle-aged whom I loathe since getting sick, and when some heart-shaped ass asks, "Can I take this pose deeper by resting my head on the floor?" it is with great resolve that I resist saying oh fuck off.
I like fish pose. I guess because I like knocking on the door of my armor. Hello? I ask. Who's there? Why the stiff-as-iron cage around your heart?