Redfish and Red salmon

Redfish noun - Large edible fish found off coast of United States from Massachusetts to Mexico.

Red salmon and redfish are semantically related. In some cases you can use "Red salmon" instead a noun "Redfish".

Red salmon noun - Small salmon with red flesh; found in rivers and tributaries of the northern Pacific and valued as food; adults die after spawning.

Redfish and red salmon are semantically related. You can use "Redfish" instead a noun phrase "Red salmon".