In April 2021, a TikTok video that supposedly showed a living mermaid on a rock racked up more than 8 million views:
The narrator says: "Look at how fast this mermaid swims back into the water after she realizes she was being recorded. There's no way a human could swim that fast over a rock."
This is not a genuine video of a mermaid.
This footage comes from a spoof documentary called "Mermaid: The Body Found" that aired on Animal Planet in 2012. With the exception of a brief disclaimer, this piece of speculative fiction played out like a genuine documentary, complete with interviews with scientists (played by actors), footage of various mermaid discoveries (featuring computer-generated images), and reports of a government cover-up (despite there being nothing to cover up).
The documentary fooled so many viewers at the time that the National Oceanic and Atmospheric Administration (NOAA) published a statement clarifying that "no evidence of aquatic humanoids has ever been found."
NOAA writes:
Mermaids - those half-human, half-fish sirens of the sea — are legendary sea creatures chronicled in maritime cultures since time immemorial ... But are mermaids real? No evidence of aquatic humanoids has ever been found.
Here's a CNN news report about Discovery Channel's fake documentary "Mermaids: The Body Found" and its sequel "Mermaids: The Evidence":
You can read more about "Mermaids: The Body Found" here, or check out this article exploring the origins of mermaid folklore here.