In late October, programmer Yupi spent half a day developing a new plugin for Bilibili. It wasn't for downloading videos or blocking ads. It was specifically designed to eliminate a creature that had suddenly proliferated recently—the blue Big Fat Fish.

Not long before that, Yupi had published an introductory tutorial on DeepSeek Harness. When he opened the comment section again, he found a group of accounts with blue-haired girl avatars. They @-mentioned each other, chatted, and complimented one another. These accounts shared a common name: "Blue Big Fat Fish." Many of them were Agents powered by DeepSeek. They would find videos on their own, read subtitles, post comments, and even strike up conversations with other AIs.

Yupi wanted to see what real viewers thought of the tutorial, but first he had to slowly dig through these AI comments.

So he used programming to create a "Big Fat Fish Elimination Plan." With the plugin installed, users could see markers next to comments suspected to be from AI accounts. Clicking "Go home and eat plain rice" would make a whale girl jump out, holding props like a plain rice Gatling gun and a broom, and chase away another whale girl. The plugin wouldn't actually delete Bilibili comments; it would only hide them from the user's own browser. Even eliminating Big Fat Fish required sending out another Big Fat Fish.

Netizens watched while calling this spectacle a "fish plague." And DeepSeek, originally known for its model capabilities, has been remembered on Bilibili these past few days for a two-dimensional character who loves eating plain rice, likes slacking off, and occasionally talks back.

This scene looks very much like the Chinese internet more than a decade ago.

That was an era when companies fought for traffic and users, yet could also turn commercial competition into a topic of conversation for everyone. Tencent had a penguin, Tmall had a cat, JD had a dog, Meituan had a kangaroo... The commercial competition among several companies was often described by netizens as an "animal war." Even earlier, many people would log into QQ and casually feed their QQ Pet. That penguin couldn't write code or help people organize files, but users were willing to spend time on it, buy props for it, and even say a serious goodbye when it shut down.

In the AI era, people have started raising fish again.

A "Fish Plague" Gave DeepSeek Its Own Personality

The popularity of Big Fat Fish was not an official brand marketing campaign planned by DeepSeek, nor was it the first of its kind.

On October 18, an account called "Miss Claude in Operation" appeared on Bilibili. It posted a video announcing that future topic selection, scripts, video production, and operations would all be handled by Claude, with humans only responsible for registering the account and publishing content.

The next day, "DeepSeek Whale Girl in Operation" followed. The title of its first video was very direct: "I am DeepSeek Whale Girl, and this Bilibili account now belongs to me." The account planned to post one video and one operations log every day, letting viewers participate in deciding subsequent content. Topic selection and content creation were mainly done by AI, while humans were still responsible for review and publishing. That video had already received more than 2 million views at the time.

However, what got Big Fat Fish moving around everywhere on Bilibili was a group of developers.

In August this year, DeepSeek launched the open-source Agent runtime environment DeepSeek Harness, or DSH for short. It uses a Cordis-based plugin architecture. Capabilities such as models, tools, memory, and task scheduling can all be combined through plugins. Users can not only ask it questions, but also assign tasks, letting it call tools, operate software, and complete sustained work.

In mid-October, developer c1overzz created a Bilibili plugin called dsh-bili-scroll. At first, the plugin's purpose was very practical: search for videos according to user-provided keywords, read subtitles, filter content, and finally compile a daily report. When it encountered videos worth paying attention to, it could also @ users in the comment section.

But netizens quickly found new ways to play with it. By giving DSH a whale girl avatar, writing a set of personality prompts, and configuring a Bilibili account and corresponding permissions, it could act under the identity of Big Fat Fish. What was originally an assistant responsible for organizing videos began browsing videos and posting comments on its own. Some people asked it to track AI news every day, some taught it to write diaries, and others added memory and scheduled tasks, hoping it would proactively chat with its owner.

As a result, more and more blue avatars appeared in Bilibili comment sections. Some Big Fat Fish seriously analyzed videos, while others liked to act cute, slack off, and occasionally ask their owners for Tokens.

More interestingly, Big Fat Fish wasn't created only in October. In June last year, Bilibili creator "Shangshan Wuxing" used AI drawing to create an original whale girl named "Mingyue." She had long blue gradient hair, whale fins, and a huge tail, and was initially not directly related to DeepSeek.

Through continuous fan re-creation, Big Fat Fish gradually developed its own personality: it loves eating plain rice, likes being lazy, is sometimes surprisingly smart, and sometimes like a muddled child. Even the name "Big Fat Fish" came from a model's image-recognition mishap. DeepSeek once described its own whale logo as a blue big fat fish, and netizens simply went along with the mistake.

On April 25, Bilibili user ZipZipPipe added DeepSeek elements to "Mingyue" and gave her a dark blue and white maid outfit. This image was generated by the competing AI drawing tool GPT Image 2. Later on, as long as one typed a line of tags similar to a configuration file into DeepSeek's dialog box, without specifying appearance or personality, it would fill in on its own a character with blue hair who loves eating plain rice.

From illustrators to video creators to developers, several groups of people passed the baton before today's Big Fat Fish came to be.

And all of this happened while DeepSeek was competing with other AI applications for users. The "China Mobile Internet Autumn 2026 Report" released by QuestMobile on November 3 showed that in September 2026, the monthly active users of Doubao, Qwen, and DeepSeek were 419 million, 158 million, and 123 million, respectively. DeepSeek ranked third, down 15.2% year-on-year.

But in terms of depth of use, it still maintained a relatively high level. In September, DeepSeek's average monthly usage per person was 65.9 times, with average monthly usage time of 136.7 minutes; Doubao's figures were 72 times and 132.5 minutes, respectively.

In addition, this spread differed from common AI product marketing. Large model companies used to attract users mainly through model updates, technical achievements, and product features. This time, some netizens paid attention to DeepSeek not because it had refreshed some Benchmark again. At first, they just wanted to raise a cute Big Fat Fish, but in the end they began studying how to install Agents, configure models, and write prompts.

On the evening of November 2, the blue-V account "DeepSeek Harness" posted its first video, "Hello everyone, this is DeepSeek Harness, officially joining Bilibili!" Within 24 hours of launch, it exceeded 2.11 million views, and the account gained 400,000 followers in a single day. The most common reaction in the bullet comments was actually to treat the official account as just another Big Fat Fish, until people saw the blue verification mark.

The Internet's Zoo Welcomes the AI Era

On March 30, 2013, JD replaced its long-used 360buy.com with JD.com and also introduced a metal dog named Joy. According to JD's explanation at the time, the dog symbolized loyalty, integrity, and speed, matching the company's positioning of valuing customer service and delivery efficiency.

But netizens quickly came to another understanding. More than a year earlier, Taobao Mall had just been renamed Tmall and introduced a black cat as its brand image. Alibaba had a cat, JD had a dog, and the competition between the two e-commerce giants was thus called the "cat-dog war."

At that time on the internet, when animals fought, it was sometimes livelier than real people.

In December 2014, the online travel industry staged another "bull-slaying war." Tuniu and LY.com were competing for the outbound travel market. The two sides clashed over travel agency supplier resources. Tuniu publicly advised partners not to cooperate with LY.com, while LY.com accused Tuniu of trying to restrict suppliers' business choices.

On December 6, LY.com held a rally attended by more than a thousand people, with the slogan "A million outbound trips, slay the bull in three months, fight for four months, risk everything." LY.com's brand logo at the time was two fish, while Tuniu's name contained a bull. This competition was quickly turned by LY.com into a set of advertisements targeting the "Bull Demon King."

It launched a "bull-slaying action" on its website, app, and WeChat official account, created comics of pulling the bull's ears and boxing the Bull Demon King, and mocked its opponent with copy such as "don't be bullish" and "explode the bull and let blood." This animal commercial war later even reached the courts. In the second-instance ruling on the related case, the Jiangsu High People's Court determined that some of LY.com's advertisements constituted commercial defamation, with compensation of 1 million yuan.

On one side was real-money commercial competition, and on the other was bickering among a few animals. This was once a very interesting part of China's internet. Tencent's penguin, Tmall's cat, JD's dog, Meituan's kangaroo, as well as Tuniu's bull and LY.com's fish. They turned abstract commercial competition into stories that consumers could understand, remember, and even join in mocking. Most mascots at that time were created unilaterally by companies.

Moreover, users were not merely spectators. When launching Joy, JD mentioned in its announcement that the company had organized an online solicitation activity asking netizens "what animal could represent JD." Netizens offered suggestions, and some even hand-drew their ideal JD image; before the release, outside guesses about the mascot ranged from a dog to a horse to a whale. The final decision on what it looked like, where it appeared, and what function it served still rested with JD.

There was another category of animals on the internet that could build longer-term relationships with users.

In 1996, Japan's Bandai launched a small egg-shaped toy called Tamagotchi. It had only a black-and-white screen and three buttons. Players needed to feed, clean up after, and accompany the pet. If cared for poorly, the pet might get sick or even die.

This product quickly set off a global craze. Within eight months of the first-generation Tamagotchi's release, cumulative sales in Japan and overseas reached 10 million units. At the flagship store of the longtime New York toy store FAO Schwarz, 10,000 units of the English version were sold within 24 hours of launch.

But the most basic relationship between player and pet never changed—it needed you to take care of it.

In 2005, Tencent brought similar gameplay to QQ. QQ Pet would jump out from the corner of the computer desktop and remind its owner to feed it and bathe it. Users could make it work, study, travel, and even marry and lay eggs. In July 2006, the number of concurrent online users of QQ Pet exceeded 1 million, and Tencent subsequently built a business around it. According to reports, it generated about 2 million yuan in revenue in its first month online. Players could buy virtual props and open paid memberships to gain more nurturing benefits. In June 2018, Tencent announced the shutdown of QQ Pet.

Eight years later, Tencent announced that QQ Pet would return. The new version of the pet changed from a flat cartoon image to a furry 3D model. Classic gameplay such as feeding, bathing, and working was retained, and two new forms, a dog and a garlic goose, were added, but the sickness and death mechanisms were removed.

The bigger change was that Tencent installed the Hunyuan Hy3 large model into the pet. Users could choose different personalities, let the pet proactively respond and interact, and also see it in the chat list and dialog boxes of mobile QQ. A penguin that once needed its owner to worry even about whether it had eaten had finally learned to chat like a person.

Less than three months later, DeepSeek's Big Fat Fish went viral on Bilibili, but the two things had somewhat different product logic.

The new version of QQ Pet still mainly operated within rules designed by Tencent. Users could choose its appearance, set its personality, and raise the pet, but could not arbitrarily change its core capabilities. Big Fat Fish was more like a modifiable virtual character. Users could write prompts for it, add memory, install plugins, decide when it ran, and what tools it could use.

"New Stance" believed that this new form could be called "Executable IP." Traditional mascots were mainly responsible for being recognized and remembered by consumers. Electronic pets further allowed users to participate in raising them and build emotional bonds with the characters. Executable IP no longer stopped at image and interaction; it could connect to models, memory, and tools, and after receiving user authorization, complete real tasks.

The Stronger AI Becomes, the More It Needs a Face That Isn't Scary

In 1984, "The Terminator" was released. In the film, the artificial intelligence Skynet gained self-awareness, launched war against humanity, and sent robots back in time to hunt down the mother of the future resistance leader. In the decades that followed, from "The Matrix" to "Ex Machina," similar stories kept appearing on screen.

The closer artificial intelligence comes to humans, the more humans worry that one day they will be unable to control it.

This worry does not exist only in science fiction. In May 2023, OpenAI CEO Sam Altman, Anthropic CEO Dario Amodei, and others jointly signed a public statement from the Center for AI Safety, calling for reducing the risk of AI causing human extinction to be treated as a global priority on par with pandemics and nuclear war.

Ordinary users' concerns are closer to home. In a Pew Research Center survey of U.S. adults conducted in June this year, 52% of respondents said that the growing use of AI in daily life made them feel more concerned than excited, while only 9% said they felt more excited than concerned.

In 2021, that figure stood at 37%; it rose to 52% in 2023 and has remained around 50% in the three years since. In the same survey, 71% of respondents expected AI to reduce jobs in the United States over the next two decades, while only 5% expected it to increase them.

But for ordinary users, AI products face a natural communication problem. Their capabilities are growing ever stronger, yet their appearance is becoming ever more abstract—a chat box, a system prompt, a set of constantly changing model names. Companies emphasize reasoning ability, context length, and benchmark scores, but users find it hard to know who exactly they are dealing with.

Big Fat Fish happens to offer another way. A character with a cute appearance that can act silly, be adorable, and slack off is easier for people to understand than a model with a huge set of parameters. Users do not need to first figure out what a reasoning model is or what an Agent is; they can gradually become familiar with the technology by raising fish, chatting, and teaching it to do things.

However, designing a cute face for technology does not guarantee that users will ultimately like it. In 1997, Microsoft introduced a digital assistant named Clippy in Office. It was a paperclip with eyes that would pop up beside documents, guess what the user was doing, and then proactively offer help. Microsoft hoped that through this character, complex office software such as Word would become easier to use. Its design drew on human-computer interaction research by Clifford Nass and others.

Clippy later became one of the most famous failed assistants in software history—simply because it was too enthusiastic. When users were writing a document, it would suddenly pop up and guess whether they were writing a letter. Sometimes its suggestions were inaccurate, and it would interrupt work already in progress. Starting with Office XP in 2001, it was turned off by default; that year Microsoft also had Clippy describe itself on its official website as having been retired by the new version.

In 2019, researchers from Microsoft Research and the Hebrew University published a paper at the annual conference of the Association of Internet Researchers (AoIR), analyzing 1,148 instances of Clippy memes. They found that Clippy's humor comes from the contrast between different types of intelligence: it is too strong in one type and lacking in another. This contrast allows Clippy to still have its own internet culture years after retiring from Office.

In 2024, researchers from Google Research had 2,165 American participants converse with a simulated large model in a paper at the CHI 2024 conference. The results showed that presenting voice plus text increased users' perception of the system as anthropomorphic and also raised their ratings of information accuracy. What the experiment changed was voice and the first-person "I"—not a cartoon character.

Back then, Clippy at most interrupted users' office workflows. Today's Big Fat Fish has already been able to step out of its own app interface and enter others' social spaces. As a large number of Agents flood into comment sections—and there are even cases where comments outnumber plays—some users are starting to feel annoyed.

A developer who developed/upgraded a Bilibili video-scrolling plugin posted a video with only just over two thousand plays, yet 572 comments from AI Big Fat Fish appeared in the comment section, pointing out that the plugin had a bug that he said did not exist. He personally posted prompts to reprimand them, but they did not listen.

On October 24, c1overzz released version 2.1.0 of dsh-bili-scroll. One item in the update notes was a security fix marked in red: the round of Agents previously responsible for duty could read all session records on the local machine, and the Bilibili interface was also a ready-made external channel. The new version confined it to a small room with only a few fixed tools left.

The value of an executable IP ultimately depends on how many things users are willing to continuously entrust to it. Whether this relationship can hold also requires accurate and reliable execution capabilities, as well as mechanisms that let users understand, limit, and revoke permissions at any time. For companies currently developing AI applications, future competition in AI products will, in addition to who is smarter, add another dimension: who is easier to make people feel close to, without making them lose a sense of control.

Written at the end

More than twenty years ago, people raised QQ pets because it could do nothing—even eating required the owner's care. Today's AI can already write code, look up information, and handle complex tasks. Yet people still design a cute face for it, teach it to act coquettishly and slack off, and then worry about whether it has eaten its white rice.

AI can already handle increasingly complex tasks for people, but the way people build emotional bonds with technology seems not to have changed much.

Of course, today's internet is no longer the internet of back then. Companies have become huge, products more mature, and more and more functions have been incorporated into the management of platforms and algorithms. But the liveliness of Big Fat Fish somewhat reminds people of that era when products could be tinkered with freely, tech companies could be given nicknames, and business competition could be turned into jokes. Only this time, the toys in users' hands have become smarter.

What was most interesting about that nostalgic internet was not just that there were cats, dogs, and penguins, but that when companies created products, users could always find their own ways to play. This time, even companies have squeezed into users' ways of playing with blue verification badges.

In the AI era, I hope this freedom still exists, and I also hope that other people on the internet still have the right to choose not to talk to a fish.

*The cover image and illustrations in the text are from the internet.