Blue catfish (Ictalurus)
Blue catfish are a popular sport fish that closely resembles its relative, the channel catfish. The scientific name, Ictalurus farcatus, translates to, fish cat, and forked, which aptly describe these fish. They have barbels, or whiskers around the mouth and a forked tail.
The coloring of a blue catfish is predominantly blue-gray to gray-blue, though they occasionally take on a silver appearance. The belly is usually a lighter shade of their main body color and fades toward white at the very bottom. Generally speaking, they have no other markings, though the version found in the Rio Grande River has dark spots on the back and sides. Their skin is smooth with no scales.
The body of the blue catfish is round with a flat belly. As they grow larger they develop a distinct hump on the back near the front of the dorsal fin.Blue catfish have a long anal fin with a straight margin. With 30 to 35 rays of near equal length, this fin looks as if it has been trimmed with scissors.
Blue catfish are often confused with channel catfish due to their similar appearance, especially at small sizes. One difference is the blue cat's head size, which tends to be larger and rounder than the channel cat's and their body, more robust. Another distinctive feature is the blue cat's anal fin, which is long and straight, where the channel cat's is more rounded. In many cases, the lack of spots on the body will also distinguish it from the channel cat.
Blue catfish are mainly nocturnal (nighttime) eaters and search for most of their food on or near the bottom. Their barbels give these fish a strong sense of smell, which plays a key role in locating food. Though blue catfish will eat nearly anything that is available, their preferred diet includes small fish, crayfish, frogs, clams, mussels, and insects. Depending on what is available, they will consume both live and dead organisms. Large blue catfish often feed exclusively on other fish.
Blue catfish are a warm-water fish found primarily in large rivers and lakes. They are native in the Mississippi, Missouri, and Ohio Rivers and their large tributaries. This encompasses a region extending from Minnesota and South Dakota south through Texas, Mexico, and northern Guatemala east to the Appalachians.
They have been introduced with some success outside this range. Blue catfish have adapted quite well when stocked in large rivers and reservoirs with suitable habitat, and are now present in large numbers in the southern United States.
Blue catfish are found mainly in large river systems and reservoirs, though they do inhabit streams, small rivers and even some natural lakes and ponds. Unlike channel and flathead catfish, the blue prefers clean (non-turbid) rivers with a relatively swift current flow. Their ideal temperature range is between 70 and 82 degrees F, though they will tolerate much lower and slightly higher temperatures throughout the year.
Their preferred environment in large rivers, is the deeper areas that have a moderate to strong current. Within these areas, blue catfish generally seek out deep holes with abundant cover that provide relief from strong currents, but they will move up to swift water to feed, primarily at night. Outside bends in rivers, tailwaters below dams, creek mouths and discharges are all common blue cat locations.
In large reservoirs, they seek many of the same features as they do in rivers: deep, secluded areas with plenty of brush and other natural or man-made cover. The absence of current in many reservoirs causes blue catfish to cover more water when searching for food, which often brings them shallow during peak feeding periods. Therefore, they often seek areas that provide both the security of deep water and the easy access to shallow feeding areas.
- Biologists estimate that blue catfish can reach 150 pounds, although none that large have ever been caught and weighed on certified scales. In 1879, a 150-pound specimen from the Mississippi River was found in a St. Louis market and sent to the United States National Museum. Legends exist about 300 and 350-pound blue catfish, but none have ever been documented.
- Blue catfish in the Mississippi River are rumored to be triggered into feeding by the passing of large ships and barges.