Considered the largest species of catfish in the United States, blue catfish are opportunistic predators and will eat any species of fish they can catch, along with crayfish, freshwater mussels, frogs and other readily available aquatic food sources. They have barbels (whiskers) around the mouth, a forked tail, and are sometimes very similar to channel catfish. The number of rays in the anal fin is typically 30-35, and coloration is usually slate blue on the back, shading to white on the belly. 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. These large catfish have also been introduced in a number of reservoirs and rivers, tending to favor deeper water, but will make feeding and spawning forays into relatively shallow water, frequently caught in warmer climates in water as shallow as twelve inches.
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. They prefer non-turbid rivers with swift current flows.
They are distributed primarily in the Mississippi River drainage including the Missouri, Ohio, Tennessee and Arkansas rivers. The range also extends south through Texas, Mexico, and into northern Guatemala.