Esox is a genus of freshwater fish, the only living genus in the family Esocidae—the esocids which were endemic to North America, Europe and Eurasia during the Paleogene through present.The species of this genus are known as pike and pickerel, and in heraldry a fish of the genus is usually called a lucy (English heraldry) or a ged (Scottish heraldry). The type species is E.