The flathead catfish (Pylodictis olivaris)is a species of North American freshwater catfish. This is the only species of the genus Pylodictis. Ranging from the lower Great Lakes region to northern Mexico, they have been widely introduced and are an invasive species in some areas. Their native range includes a broad area west of the Appalachian Mountains encompassing large rivers of the Mississippi, Missouri, and Ohio basins. The range extends as far north as Canada, as far west as Arizona, and south to the Gulf of Mexico including northeastern Mexico. Flatheads cannot live in full strength seawater, but they can stand up to about 10 parts per thousand for a while and will live pretty happily up to about 5 ppt. Flatheads grow to a length of 155 cm (61 in) and may weigh up to 56 kg (123 lb). The average length is about 25-46 inches (64-117 cm). Their maximum recorded lifespan is 24 years. The world angling record flathead catfish was caught May 14, 1998, from Elk City Reservoir, Kansas, and weighed 123 lb 9 oz (56.0 kg).