Yes, cory catfish clean the tank. Cory catfish are bottom feeders, and as a result, they’re also efficient tank cleaners. Cory catfish will eat leftover food other fish don’t eat, and sometimes even fish poop.
They scavenge for food from the ground and even from the tiniest crevices. This means cory catfish can help keep the tank cleaner and even maintain the water quality.
With that said, you’ll still need to clean your tank regularly to keep cory catfish healthy. Change at least 20% of the tank’s water once a week and clean the tank once a month. If possible, you should also test the water quality regularly to keep the cory catfish happy.