EXCLUSIVE: Discovery Channel’s Shark Week clocked its biggest audience in its 26-year history Sunday night. Nearly 5 million “fin-atics”  (blame Discovery, not me) tuned in for the two-hour fake docu, Megalodon: The Monster Shark Lives – not all of them happily. Megalodon was up 141% in the 25-54 demo compared to the same two hours of 2012. Later, Shark After Dark, Shark Week’s first ever late-night talk show, clocked 2.1 million viewers. Discovery noted this afternoon that Shark Week continues to dominate social conversation year after year. On Sunday, it was responsible for the #1 most social show  — Megalodon — across broadcast and cable, according to SocialGuide, beating the NFL Hall of Fame Game — and even Justin Bieber: Never Say Never! Shark Week conversation on Twitter grew 66%, year over year, in primetime and late night, and was responsible for nearly 1 million Tweets for the day.

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According to Facebook, Shark Week generated 3.4 million total interactions Sunday, and #SharkWeek was the top hashtag on the platform. Meanwhile, #Megalodon, Megalodon and #SharkAfterDark all trended worldwide on Twitter, in addition to #SharkWeek, Shark Week and #AirJaws trending in the United States. But a lot of that Facebook noise was not happy. Discovery’s Shark Week Facebook page on Monday was drowning in angry comments about Megalodon from some of those “fin-atics.” In keeping with this year’s more “humorous” approach to Shark Week, the network kicked things off with two-hour fake docu  –  which resembled those fake mermaid docus Discovery has run to record crowds.

Shark Week’s Facebook page looked kind of like this:

*We don’t want phony fakeumentary, we want sharks not actors you clowns

*There is nothing to celebrate while you show fake documentaries. Fire the person who decided to put fake info into shark week!!!!!

*I cannot believe I wasted 2 hours watching a FAKE documentary about a FAKE event! Deplorable! You lost my viewership permanently! Who’s dumb idea was this???

*You gonna have a two hour program where you get a bunch of “marine biologists” to sit down & theorize that this cake could become the preferred food of sharks everywhere? ….F*** off Discovery Channel. You’re a joke & I won’t be watching.

*Last night’s mockumentary killed my usual enthusiasm for Shark Week too. How can I trust anything you show anymore to have any basis in fact?

*How about you NEVER air that sorry excuse for a show “megladon” ever AGAIN!!!!! Discovery should be ashamed and people should be fired and deported.

Some were more measured in their reaction:

*Okay folks. We all agree that the Megalodon nonsense from last night was a disaster. Now let’s focus on the potential for a return to our regularly anticipated actual shark science tonight: a scientist using new tech to track sharks on the east coast, and a special on the bull sharks in Louisiana.

And others just refused to join the caterwauling:

*Why is everyone so mad about last nights show? I actually found it very entertaining. Would you rather have seen “Air Jaws” for the twentieth time?

Contacted for comment, Shark Week exec producer Michael Sorensen said to Megalodon non-fans: “With a whole week of Shark Week programming ahead of us, we wanted to explore the possibilities of Megalodon. It’s one of the most debated shark discussions of all time, can Megalodon exist today? It’s Ultimate Shark Week fantasy. The stories have been out there for years and with 95% of the ocean unexplored, who really knows?”

The network had run a “disclaimer” with Megalodon, though if you blinked you missed it: None of the institutions or agencies that appear in the film are affiliated with it in any way, nor have approved its contents. Though certain events and characters in this film have been dramatized, sightings of “Submarine” continue to this day. Megalodon was a real shark. Legends of giant sharks persist all over the world. There is still debate about what they might be.