glaucus), also called the blue pike, was a unique color morph (formerly considered a subspecies) of walleye which was endemic to the Great Lakes of North America.

Morphometric studies led biologists to classify the blue walleye as a separate species in 1926, although it was later downgraded to a subspecies.

[1] Based on morphological study, Carl Leavitt Hubbs declared the blue walleye to be a separate species in 1926.

[4] The United States declared blue walleye an endangered species in 1967,[5][6][7] and extinct in 1983.

[14] A mucosal pigment, named "sandercyanin", was hypothesized to be the source of the color,[15] but this has not been confirmed.