In some parts of China, mainly coastal, when a whole fish is served it is customary to pick away the flesh on the uppermost side until the spine is exposed and the flesh on that side all gone. Then the bones are lifted out as described by @Shalmanese and eating of the lower part commences. On no account is the fish flipped on the serving plate. That would be terribly taboo. It is seen as suggestive of a fishing boat capsizing, and so an omen of bad luck.
In other places, the fish is happily flipped.
