Appearance
The blue catfish is a long fish with a flat dorsal fin and deeply forked tail. Its smooth skin lacks scales. It has a slate blue body, a silver-white belly and four pairs of black, whisker-like barbels around its mouth. Adults usually grow to be less than two feet long, but can be as long as five feet and weigh more than 100 pounds.
Feeding
Blue catfish are opportunistic bottom-feeders. Their varied diet includes worms, clams, small crustaceans, mussels, crabs, insects, frogs and variety of smaller fish, including other blue catfish. They prefer large rivers with deep channels, swift currents and sandy bottoms. They seek cooler waters in summer and warmer waters in winter.
Blue catfish are nocturnal. During the day, they stay near the bottom of deep, restrictive waters. At night, they swim to faster flowing waters to hunt for food. However, their diet varies seasonally, and in spring, summer and fall, a large portion of the blue catfish’s diet is made up of underwater vegetation.
Blue catfish have the ability to “taste” their surroundings with sensory tissues on their barbels and skin, which they use to detect and hunt prey. To avoid predation, young blue catfish will often hunt at night, feeding primarily on zooplankton and small aquatic insects.
Predators
While adult blue catfish have few natural predators in the Chesapeake Bay watershed, they are among the preferred prey of both osprey and bald eagles.
When attacked, blue catfish defend themselves with serrated spinal barbs located on both their dorsal and pectoral fins. The spines have glands that expel harmful toxins, which can enter predators’ wounds and cause sharp pain.
Reproduction and life cycle
Spawning occurs once per year between April and June, often in lower-salinity streams and smaller tributaries. Blue catfish mate with only one partner per reproductive cycle. Male blue catfish build nests in dark, protected areas, such as under rocks or in submerged logs and man-made containers. When preparing their nesting sites, males use their tails to sweep aside debris and use their jaws to remove larger objects. Their nests range from six to 14 inches in diameter.
Once they have prepared the nest’s foundation, males release pheromones that attract females to the nest. Males and females then court by swimming in elaborate patterns. Blue catfish reproduce at a rapid rate, with females producing 4,000 to 8,000 eggs per kilogram of body weight. Once the eggs have been fertilized, male blue catfish often force females away from the nest to organize and protect the eggs.
Young often form tight schools after hatching. While both parents assist in raising the young, male catfish often act as the primary caretaker. Blue catfish live nine to 10 years on average, though some have been known to live up to 25 years.
Did you know?
- Blue catfish are a popular recreational catch.
- The largest blue catfish caught in Maryland weighed 84 pounds, and was caught in the Potomac River in 2012. The largest blue catfish caught in Virginia weighed 102 pounds, and was caught in the James River in 2009.
- Blue catfish were introduced to the region in the 1970s, and are now considered an invasive species. Their growing numbers and rapid expansion throughout the region have raised concern about their potential impact on menhaden, blue crabs and other native species that play an important role in our ecosystem and economy.
- The Chesapeake Bay Program’s Sustainable Fisheries Goal Implementation Team adopted an Invasive Catfish Policy statement, which outlines the need to control the effects of these invasive fish. The Goal Team’s Invasive Catfish Task Force released two reports synthesizing what is known about invasive catfish and offering recommendations for managing their spread.
Sources and additional information
