Facing the East China Sea, seafood in Shanghai is very popular. However, due to its location among the rivers, lakes, and canals of the Yangtze Delta, locals favor freshwater produce just as much as saltwater products like crabs, oysters, and seaweed. The most notable local delicacy is Shanghai Hairy crab.
Below are two most famous sea food in Shanghai.

Steamed Crab:Da Zha Xie
Da Zha Xie is a special type of crab found in rivers, and is normally consumed in the winter. The crabs are tied with ropes or strings, placed in bamboo containers, steamed and served. There few other artificial ingredients added to the dish yet it tastes fantastically good. Da Zha Xie is usually consumed with vinegar. Locals are also quite fussy about when to consume male crabs and when to consume female crabs.

Smoked Fish Slices
An ideal menu for those who like highly spiced food. the Smoked Fish Slices (fresh fish marinated and spiced to taste like smoked fish) make a delicious, unusual hors doeuvre, while the strong-tasting Stewed Pork Flavoured with Dried Squid dish is offset by the vegetable rice to make a substantial meal.

Besides, there are a lot of street food, cheap but delicious. I would like to make a collection of their pictures.