Named for their six prominent barbels, which give the image of cat-like whiskers. It is a scaleless fresh-water catfish recognizable by its broad, flat head and wide mouth.

The wels catfish is the only native catfish species of Europe, besides the much smaller related Aristotle catfish found in Greece. Mythology and literature record wels catfish of astounding proportions but the average size of the species is about 1.2 m to 1.6 m, up to 2 m. The largest specimens on record measure more than 2.5 m in length and sometimes exeeded 100 kg.