Photo credit: Duane Raver, US Fish and Wildlife Service, Bugwood.org
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Species at a Glance
Often confused with the channel catfish (Ictalurus punctatus), the blue catfish is the largest species of North American catfish, reaching up to 150 pounds and living up to 20 years. Populations of non-native catfish such as the blue and channel catfish have increased dramatically since their introduction, and are now present in every major Chesapeake Bay tributary.
The long, heavy body of the blue catfish is smooth and scaleless with a wide head and a high spot near the center of the head called the dorsal hump. The upper jaw protrudes well beyond the lower. It has a slate blue body above, fading to silver-white on the sides and belly. The outer margin of the anal fin is straight, and the caudal fin is deeply forked. Four pairs of black, whisker-like barbels appear around the mouth. Adults usually grow to be less than 0.6 m (2 ft) long, but can be as long as 1.5 m (5 ft) and weigh more than 45 kg (100 lbs).
Small blue catfish are often confused with channel catfish. The channel catfish rarely exceeds 14 kg (30 lbs) and smaller individuals often have dark spots that are not found on the blue catfish. Large channel catfish and medium-sized blue catfish can be more difficult to tell apart, often having similar coloration and general body shape. The margin of the anal fin can be used to differentiate these fish. The blue catfish has an anal fin with a very straight margin and the channel catfish has a rounded margin. They can also be distinguished by counting fin rays in the anal fin; 30-35 rays in the blue catfish and 25-29 rays in the channel catfish.
While the blue catfish lives primarily in freshwater, it can thrive in brackish waters and has a high tolerance for different habitats and water conditions. It is a bottom dweller, preferring large rivers with deep channels, swift currents, and sandy bottoms.
Intentionally stocked as a food fish, sport fish, and to feed on populations of the invasive Asian clam, the blue catfish has established and spread to new locations through connected waterways, and by escaping catfish farms during floods. With a long lifespan and females producing 4,000 to 8,000 eggs per kilogram of body weight, it has continued to expand its range and population.
Native to the Mississippi, Missouri, and Ohio River basins, the blue catfish has been stocked in at least 20 states. During the 1970s and 1980s, they were introduced into the James, Rappahannock, and York rivers in Virginia and populations have expanded into nearly every major tributary in the Chesapeake Bay watershed.
Note: Distribution data for this species may have changed since the publication of the Mid-Atlantic Field Guide to Aquatic Invasive Species (2016), the source of information for this description.
*To learn more about the native/invasive range of the blue catfish in Pennsylvania, check out the information available for this species on our Invasive Here but Not There page.
Because of its adaptability, diverse diet, large size, and growing numbers, there is concern about the potential impacts blue catfish may have on native species of fish and shellfish in the Chesapeake Bay. In some studies on the James and Rappahannock rivers, invasive catfish such as the blue and flathead catfish have been estimated to compose up to 75 percent of the total weight of all fish inhabiting certain stream reaches.
Information for this species profile comes from the Mid-Atlantic Field Guide to Aquatic Invasive Species (2016).