blueback
Immature sockeye salmon
Blueback refers to various fish species distinguished by blue coloring on their backs, including a type of salmon, trout, or herring depending on region.
In American history, bluebacks were Confederate currency notes during the Civil War, named for their blue-tinted reverse side—contrasting with Union greenbacks.
The term also describes certain old or rare books with blue cloth bindings.
sockeye
Alaska's prized salmon
migration · fry · smolt · parr · alevin · anadromous · hatchery · escapement · lifecycle · freshwater
alewife
Small herringlike fish
forage · schooling · commercial · Chesapeake · seine · run · coastal · migratory · catch
bluebackgreenback
US paper currency
redbelly · redback · silverside · yellowfin · yellowback
back, blue, background, backpack, backup, backbone, blueprint, backlash, bluish