Salmon Focused Investments in Sustainable Habitats Act of 2019 or the Fish Act of 2019 This bill addresses identifying, restoring, and protecting salmon conservation areas in the United States. Specifically, the bill requires the National Oceanic and Atmospheric Administration and the U.S. Fish and Wildlife Service to jointly issue guidance on the process and biological criteria required to identify salmon conservation areas; and directs the National Fish and Wildlife Foundation to provide grants to certain entities to protect or maintain salmon conservation area features and projects that are focused on conservation and restoration within conservation areas, including to restore or maintain ecological functions and processes related to salmon productivity and diversity at watershed or subwatershed scales.