Swordfish are freshwater fish, because they are mainly distributed in freshwater areas such as Yangtze River, Qiantang River and Yellow River, so they belong to freshwater fish. Although they belong to freshwater fish, they can grow in seawater. Because swordfish have migratory habits, they can not only adapt to the fresh water environment, but also grow normally in seawater. When swordfish breed, they will enter fresh water. After they breed successfully, they will lead small fish into seawater to grow. Therefore, many swordfish live at the junction of fresh water and seawater, such as Bohai Sea, Yellow Sea and East China Sea.

Swordfish will live in fresh water from late February to mid-March in spring every year, and their young fish will go down the river and grow at the junction of fresh water and seawater. When they grow up, they will enter the sea to live. Different species of swordfish have different requirements for the environment. Like the Yangtze River swordfish, they do not gather in large groups when living in seawater, but only move on the seabed. But when they enter the Yangtze River basin, they will become social animals and rise to the middle and upper classes. There are also swordfish in the Yellow River, which don't eat during the retrospective period. After entering Dongping Lake, they began to eat. After laying eggs in early June, they returned to live in the sea one after another.