A: Cleaning stations are just what the name implies, specific locations on the reef where fish get cleaned. They get cleaned by cleaner fish or other marine life. There are cleaning fish (wrasses, gobies, etc), cleaning shrimp, etc to name a few.
When a fish approaches the cleaner station they will 'pose' in some fashion to indicate that a 'truce' exists between the fish and the cleaners. Often you can watch the cleaners swim into the mouth of the larger fish, in and out of it's gills or along it's body. The cleaners are picking off parasites, dead skin and scales. At some point, the truce is over, the cleaners on cue vanish to safety and the other fish moves on. It's actually quite common to see on the reef.
If you are patient, you can even get the cleaners to give you a manicure. Pictured below, Rich at a cleaner station on Bloody Bay Wall, Cayman Islands, at about 60 feet.
