Seafood includes fish, shellfish such as mollusks and crabs, and even sea vegetables such as seaweed and algae that come from the sea. This includes freshwater in the United States.  That definition, according to the Seafood Nutrition Partnership, must also take into account the long-term viability of the food supply as well as the waterways that sustain life.  Short answer: Any manner you can acquire the sea's beneficial nutrients, vitamins, and critical omega-3 fatty acids. For More Information, Please Visit Site.