I suspected it is probably illegal to label or call a steelhead a salmon, and it appears that it is illegal (though I'm no lawyer). Notice the defintion of 'salmon' by Washington state law specifically excludes 'game fish' which would include steelhead and any other trout. RCW 69.04.932 Salmon labeling — Definitions. Unless the context clearly requires otherwise, the definitions in this section apply throughout RCW 69.04.933 through 69.04.935. (1) "Salmon" means all species of the genus Oncorhynchus, except those classified as game fish in Title 77 RCW, and includes: SCIENTIFIC NAME COMMON NAME Oncorhynchus tshawytscha Chinook salmon or king salmon Oncorhynchus kisutch Coho salmon or silver salmon Oncorhynchus keta Chum salmon Oncorhynchus gorbuscha Pink salmon Oncorhynchus nerka Sockeye salmon Salmo salar (in other than Atlantic salmon its landlocked form) (2) "Commercially caught" means salmon harvested by commercial fishers. RCW 69.04.933 Salmon labeling — Identification of species — Exceptions — Penalty. With the exception of a commercial fisher engaged in sales of fish to a fish buyer, no person may sell at wholesale or retail any fresh or frozen salmon food fish or cultured aquatic salmon without identifying the species of salmon by its common name to the buyer at the point of sale such that the buyer can make an informed decision in purchasing. A person knowingly violating this section is guilty of misbranding under this chapter. A person who receives misleading or erroneous information about the species of salmon and subsequently inaccurately identifies salmon shall not be guilty of misbranding. This section shall not apply to salmon that is minced, pulverized, coated with batter, or breaded.