Northern pike are most often olive green, shading from yellow to white along the belly.
The flank is marked with short, light bar-like spots and a few to many dark spots on the fins.
Sometimes, the fins are reddish.
Younger pike have yellow stripes along a green body; later, the stripes divide into light spots and the body turns from green to olive green.
The lower half of the gill cover lacks scales, and it has large sensory pores on its head and on the underside of its lower jaw which are part of the lateral line system.
Unlike the similar-looking and closely related muskellunge, the northern pike has light markings on a dark body background and fewer than six sensory pores on the underside of each side of the lower jaw.

A hybrid between northern pike and muskellunge is known as a tiger muskellunge (Esox masquinongy × lucius or Esox lucius × masquinongy, depending on the sex of each of the contributing species).
In the hybrids, the males are invariably sterile, while females are often fertile, and may back-cross with the parent species.
Another form of northern pike, the silver pike, is not a subspecies but rather a mutation that occurs in scattered populations.
Silver pike, sometimes called silver muskellunge, lack the rows of spots and appear silver, white, or silvery-blue in color.
When ill, silver pike have been known to display a somewhat purplish hue; long illness is also the most common cause of male sterility.

In Italy, the newly identified species Esox cisalpinus ("southern pike") was long thought to be a color variation of the northern pike, but was in 2011 announced to be a species of its own.
Northern pike are most often olive green, shading from yellow to white along the belly. The flank is marked with short, light bar-like spots and a few to many dark spots on the fins. Sometimes, the fins are reddish. Younger pike have yellow stripes along a green body; later, the stripes divide into light spots and the body turns from green to olive green. The lower half of the gill cover lacks scales, and it has large sensory pores on its head and on the underside of its lower jaw which are part of the lateral line system. Unlike the similar-looking and closely related muskellunge, the northern pike has light markings on a dark body background and fewer than six sensory pores on the underside of each side of the lower jaw.
A hybrid between northern pike and muskellunge is known as a tiger muskellunge (Esox masquinongy × lucius or Esox lucius × masquinongy, depending on the sex of each of the contributing species). In the hybrids, the males are invariably sterile, while females are often fertile, and may back-cross with the parent species. Another form of northern pike, the silver pike, is not a subspecies but rather a mutation that occurs in scattered populations. Silver pike, sometimes called silver muskellunge, lack the rows of spots and appear silver, white, or silvery-blue in color. When ill, silver pike have been known to display a somewhat purplish hue; long illness is also the most common cause of male sterility.
In Italy, the newly identified species Esox cisalpinus ("southern pike") was long thought to be a color variation of the northern pike, but was in 2011 announced to be a species of its own.
Northern pike