You probably thought all fish had scales. The fact is, no catfish has scales. Many have bony plates that look like large scales, but some do not have even these. The coloration of most catfish is restricted to shades of brown, black and white. There are a few spectacularly colored exceptions.
Many people consider catfish to be ugly or weird in appearance and a necessary evil as scavengers.
Fortunately, this outdated viewpoint is fading and people are starting to appreciate catfish in their own right. The catfish belong to not one but 32 different families, the vast majority of which come from freshwater environments. They inhabit every continent except Antarctica. They are also the most diversified of our groups. There are more than 2000 different species.