Pike are long and slender, averaging a little more than two feet in length when mature. The weight can vary greatly depending on the length of the fish. Northern pike have dark green or olive bodies with oval spots on them, usually a faded yellow in color but sometimes silver.
One of the best ways to identify fish can be their fins, which can vary in number and in shape. A telling feature on northern pike is their rounded tail tips. In contrast, many species feature tail tips that are almost dangerously sharp. Pike have four fins on their bodies in addition to the tail fin; three of the fins are located on the belly of the fish. Both the dorsal and anal fins are located toward the back of the body near the tail fin, and the dorsal fin does not have any spines on it, as do the dorsal fins of many other types of fish.
The cheeks on a northern pike are fully scaled, unlike the cheeks of a muskie, which are partially scaled and partially smooth. Muskie scale colors also tend to be lighter--the green background tends to be lighter olive on a muskie, and the spots are darker and sometimes appear as vertical bars. The underside of the fish is white, silver or cream.
Northern pike have flat, wide mouths that open to numerous sharp teeth. The size of the mouth is key to northern pike because they frequently eat fish that are as much as 1/3 their own size. Pike also have five mandible pores on each side of the jaw, while muskies have six to nine. This can be difficult to identify unless you have experience looking for fish pores, but while scale colors can sometimes be confusing, jaw pores are a clear-cut method of identification.