The Wikipedia article on this provides some background information: https://en.wikipedia.org/wiki/Euphemisms_for_Internet_censorship_in_China https://en.wikiped

The Wikipedia article on this provides some background information: https://en.wikipedia.org/wiki/Euphemisms_for_Internet_censorship_in_China https://en.wikipedia.org/wiki/Euphemisms_for_Internet_censor... > The 2004 Chinese Communist Party announcement of the goal of constructing a "harmonious society" has been cited by the government of China as the reason for Internet censorship. As a result, Chinese netizens began to use the word "harmonious/harmonize/harmonization" (和谐) as a euphemism for censorship when the word for censorship itself was censored, particularly on BBSs. Following this, the word "harmonious" itself was censored, at which point Chinese netizens began to use the word for "river crab", a near homophone for "harmonious". In a further complication of meaning, sometimes aquatic product (Chinese: 水产) is used in place of "river crab".