Esox  Esox is a genus of freshwater fish, the only living genus in the family Esocidae—the esocids which were endemic to North America and Eurasia during the Paleogene through present. The species of this genus are known as pike and pickerel. The type species is "E. lucius", the northern pike. The big pike species are native to the Palearctic and Nearctic ecozones, ranging across northern North America and from Western Europe to Siberia in Eurasia. Pikes have the elongated, torpedo-like form of predatory fishes, with sharply pointed heads and sharp teeth. Their coloration is typically grey-green with a mottled or spotted appearance with stripes along their backs, providing camouflage among weeds. Individual pike marking patterns are unique, like fingerprints. Pike can grow to a maximum recorded length of , reaching a maximum recorded weight of . Currently, seven recognized species are placed in this genus: Hybrids between "Esox masquinongy" and "Esox lucius" are well-known and referred to as the tiger muskellunge. One fossil species, "Esox kronneri", is known from the Eocene of the Green River formation, and a second, "Esox nogaicus", is known from the Pleistocene of the Ukraine. Additional species are found in Miocene ("Esox sibiricus") and Pliocene ("Esox moldavicus") deposits from the Ukraine, Poland, Kazakhstan, Mongolia, and Moldavia. Two additional fossil species, both from the Cretaceous of Alberta, Canada, are placed in their own genera: "Estesesox foxi" (Santonian to Campanian), and "Oldmanesox canadensis" (Campanian to Maastrichtian). The generic name "Esox" (pike fish) derives from the Greek ἴσοξ ("ee-soks", a large fish) and appears to be both profoundly archaic and cognate with Celtic, Welsh "eog" and Irish Gaelic "iasc" (fish), as well as alpine Gaulic "*esosk" which is consistent with the original indoeuropean root for the common word for fish, "*pei(k)sk". Pliny uses the Latin form "Esox" in reference to a large fish in the Rhine normally identified with Salmonidae ("lax" or salmon).