Does fish shrink when cooked?

Yes, fish shrinks when cooked. Cooking causes the proteins in the fish to denature and coagulate, which results in the loss of water and a reduction in size. The amount of shrinkage depends on the type of fish and the cooking method. For example, fish that are cooked in a moist environment, such as poaching or steaming, will shrink less than fish that are cooked in a dry environment, such as grilling or baking.