The state fish of Washington is the steelhead trout Salmo gairdnerii, a favorite among sport anglers that can be caught both in inland freshwater and saltwater. The fish is plentiful in the Pacific Northwest of the United States, but is also found in many other areas of North America, as well as portions of Russia. The trout has many features similar to salmon, but unlike salmon it does not die immediately after spawning.
In 1969, the steelhead trout was designated the state fish of Washington. The specific statute that gave the fish its honored designation is found in the Revised Code of Washington, Title 1, Chapter 1.20, Section 1.20.45. The statute does not offer the fish any special protection, other than a daily bag limit of two, and a minimum size of 20 inches (50.8 cm). Harvesting it can be done in accordance with state and local laws that would apply to most other fish.
Several names are used to identify the state fish of Washington. The name steelhead trout is one of the most popular, and refers specifically to the members of the species that actually venture out into the ocean. Some of the species Salmo gairdnerii actually spend their entire lives in freshwater. These freshwater fish are better known by their common name, the rainbow trout.
Biologically, there is no difference between the fish, although where they live may lead to a difference in their appearances. These differences are not the result of genetics, however, but environment. Consequently, it could be argued that the state fish of Washington is both the steelhead trout and the rainbow trout.
The steelhead trout can grow up to 55 pounds (approximately 25 kg), which is much larger than its freshwater counterpart. Generally, most have an average size well below this maximum. The state fish of Washington generally lives no longer than 11 years. it has a dark olive color on its back, with a white or silver underside. They require well oxygenated rivers with clean, flowing water, especially when they are younger.
When the steelhead is ready, it leaves the familiar confines of the river and heads out into the ocean, where it can stay for years. Eventually, if it survives long enough, it will return to the same river where it began its life to spawn. The fish will continue to live even after the spawning. An opportunistic feeder, it will go after insects, other fish, fish eggs, and zooplankton.