You searched for: “anadromous
1. Fish that spend most of their lives feeding in the open ocean, but migrate to spawn in freshwater.
2. Fish; such as, salmon and shad that return from the sea to the rivers where they were born in order to breed.

The best-known anadromous fish are salmon, which hatch in small freshwater streams, go down to the sea and dwell there for several years, then return to the same streams where they were hatched, spawn, and then die shortly thereafter.