All fish have more or less slimy substance on the outer flesh. The slime is part of a fish's mechanical defense mechanism against minor injuries and pathogenic organisms.

However, Catfish are very popular fish with a slimy flaky flesh, since they are smooth on the outer flesh with no scales, they are naturally covered with a thick slimy layer, which needs to be pulled out or scraped before boiling, smoking or cooking the fish.
The slime can be removed using different tools or by following some simple methods. here is how to clean Catfish slime in this video


https://www.youtube.com/watch?v=xZtktkPPZrI

use lemon

MPEROR:
use lemon

Of course you can also
use other methods as well.

The way you were washing that fish tail though

bigtt76:
The way you were washing that fish tail though

Hahahah, like how please?