The American paddlefish (Polyodon spathula) is one of the largest and most ancient freshwater fish in North America, often called a “living fossil” because its lineage dates back over 300 million years, predating the dinosaurs. This unique creature is easily identified by its extremely long, flattened, paddle-like snout, known as a rostrum, which can account for one-third of its total body length. The paddlefish inhabits the slow-moving, large rivers and reservoirs of the Mississippi River basin. Its entire body is smooth, lacking scales, and its skeleton is primarily composed of cartilage, much like a shark’s.
Record-Breaking Dimensions
The maximum recorded sizes for the American paddlefish represent immense dimensions that are rarely seen today. Historical accounts and records suggest that the largest specimens could exceed 7 feet in length. The official state record for an unrestricted division paddlefish, taken in Iowa in 1916, reportedly weighed 198 pounds. Some historical reports even suggest specimens weighed as much as 438 pounds.
These colossal figures are generally associated with very old fish caught decades ago, before extensive dam construction and heavy fishing pressure fragmented their habitat. More recent, confirmed state-level records still show impressive size, with several fish caught exceeding 160 pounds. A 164-pound female caught in Oklahoma in 2021, for instance, measured over 81 inches (6.75 feet) in total length. These massive records are now considered extreme outliers within modern populations.
Typical Mature Size
A typical adult paddlefish ranges from 50 to 70 inches in length and weighs between 30 and 60 pounds. The paddlefish’s average size is strongly influenced by the sex of the fish.
Female paddlefish grow substantially larger and heavier than males, a reproductive adaptation that allows them to carry a greater number of eggs. While a male paddlefish might reach a length of 5 feet and weigh 40 pounds, a mature female is more likely to be closer to 6 feet in length and weigh 60 to 70 pounds or more. This difference means that nearly all of the record-breaking fish are large, non-reproductive females.
Growth Rate and Lifespan
The ability of paddlefish to reach large sizes is linked to their slow growth rate and long lifespan. They are one of the longest-lived freshwater fish in North America, with some individuals living for 50 years or longer. The average lifespan, based on studies of their dentary bones, is estimated to be between 20 and 30 years.
This slow growth is paired with a late age of sexual maturity, particularly for females. Males typically reach sexual maturity between 7 and 9 years of age. Females, however, do not begin spawning until they are between 12 and 18 years old. This extended period of growth before reproduction allows the females to accumulate the mass necessary to produce massive quantities of eggs, explaining why they achieve a much greater final body size than the males.