The greenback cutthroat trout (Oncorhynchus clarki stomias) is the easternmost subspecies of cutthroat trout

Cutthroat trout

The cutthroat trout is a species of freshwater fish in the salmon family of order Salmoniformes. It is one of the many fish species colloquially known as trout...

. This subspecies, once widespread, today occupies less than 1% of its historical range and is currently listed as threatened

Threatened species

Threatened species are any speciesg animals, plants, fungi, etc.) which are vulnerable to endangerment in the near future.The World Conservation Union is the foremost authority on threatened species, and treats threatened species not as a single category, but as a group of three categories,...

 under the Endangered Species Act

Endangered Species Act

The Endangered Species Act of 1973 is one of the dozens of United States environmental laws passed in the 1970s. Signed into law by President Richard Nixon on December 28, 1973, it was designed to protect critically imperiled species from extinction as a "consequence of economic growth and...

. It was adopted in 1994 as the state fish of Colorado

Colorado

Colorado is a U.S. state that encompasses much of the Rocky Mountains as well as the northeastern portion of the Colorado Plateau and the western edge of the Great Plains...

.
The greenback cutthroat's maximum size is 18 inches (46 cm). It has the largest spots of all cutthroats and is reported to have the most brilliant spawning

Spawn (biology)

Spawn refers to the eggs and sperm released or deposited, usually into water, by aquatic animals. As a verb, spawn refers to the process of releasing the eggs and sperm, also called spawning...

 coloration.