Catfish unlike most fish do not have scales they have skin.
if you are talking about the slimy stuff covering the skin (I'm not 100% sure but) it's mucus.
All fish (even sharks) have a body covering of scales.
its a fur
Scales
The body covering for a fish is called its scales. Scales on fish vary by size, color, number, and shape by species.
All fish have a body covering of scales.
hair
cool
it varys
A cat's body is covered in skin. Most cats have skin that is covered by fur.
The clown fish's body is covered with scales and mucus over them.
Most bony fishes have scaly covering on body as Labeo .
Fur covers the cat.