The Fish Pose is the natural successor of the shoulder stand, and it's recommended that you practice it as a counter pose to the stand. The pose involves a compression of the spine and neck as opposed to the stretch obtained while in the shoulder stand, or the Bridge and Plough poses.
There are several benefits of the fish pose. First of all, it helps you expand the chest cavity, enabling the lungs to breathe more air and to become more accustomed to deep breathing techniques. The neck muscles and nerves also become stronger and more responsive while the spine increases in flexibility.
Begin the pose by lying down on your back with the legs straight and close together and with the spine kept straight, parallel to the floor. The position of the arms is also important: they should be straight, positioned under your thighs. The palms rest together, stuck to the floor while the elbows are as close to one another as possible.
It is time to go into the pose. Press your elbows down on the floor and arch your back. Take a deep breath as you are doing this. Keeping the weight of your body on your elbows, move your head backwards until it reaches the floor. Exhale while holding the fish pose. Relax your legs and allow your chest to expand while taking in a long breath. In order to come out of the pose, try to slowly lift your head and only then release pressure from your elbows.
courtesy By: www.yogisutras.com