If you are asking about live corals, they should not require cleaning unless water conditions are poor and nuisance algae are overgrowing everything. If this is the case, the various saltwater fish and invertebrates that do eat algae will not be able to keep up with this amount of growth. Correcting the water quality (eliminate phosphates, reduce nitrates, etc.) and verifying proper spectrum lighting will be the only longterm solution.
If, on the other hand, you are asking about dead coral skeletons, used as decoration the most common cleaning technique is to remove them, rinse or scrub them to remove as much algae as possible (no soap!!! water only) and then bleach them. Common chlorine bleach (e.g., Clorox) diluted (1 part bleach to 10 parts of water) will whiten the pieces back up. Rinse very thoroughly in fresh water and then allow to completely air dry before returning to the aquarium.
In the deep coral of reefs
The fish that eats Marlin's eggs is a barracuda, and the fish Marlin and Dory encounter deep down is a anglerfish
Clownfish live at the bottom of the sea, usually in a coral reef environment
There are many types of saltwater fish. Coastal fish live in the ocean near the shore. Deep sea fish live deep in the ocean below where the sunlight reaches. Pelagic fish live near the surface of the ocean. Demersal fish live near the bottom of a salt lake or sea. Coral reef fish live in or near coral reefs.
Hard Coral is not a fish but, some small fish live in hard coral.
Lion fish live in coral reefs. Most coral reefs occur between 100 and 300 feet deep water.
Devilfishs live in warm waters and deep waters with lots of coral.
Actually many different types of fish eat coral. Butterflies, angelfish, filefish, and parrotfish are some of the more common coral eaters.
Some fish eat of the coral reefs, but they do not live on or in the coral reefs. But every fish living on or in the coral reef has a job to do that protects it from the intrudors.
coral
parrot fish eat coral
Fish need it for food, the soil needs it for clean-up, and plants need it for filtering soil.