MiroFish is a free program for analysts, public-relations teams and researchers who want to rehearse how a crowd might react to a text. Upload a news item or draft policy and it makes up an AI character for each person and group named. The characters post and reply on imitation Twitter and Reddit networks. A final AI step writes a forecast-style report, and you can chat with any character. It needs an outside AI service, and its setup notes warn of high usage and advise starting with fewer than 40 rounds of posting.
36Kr reports that a student known as BaiFu, then a Shanda Group intern, built MiroFish in ten days with AI coding tools. Within 24 hours of his demo video, Shanda’s founder, Chen Tianqiao, decided the group would invest 30 million yuan (about US$4 million) in the project. Simile, which sells simulated consumers to companies, raised over $200 million at a $2 billion valuation in July 2026.
WPP’s research site reports one complete test day, May 14, 2026, which it calls too small a sample. MiroFish and a plain Gemini request both said the S&P 500 would fall. The index closed up 0.77%. The test got about 25 agents, not the README’s thousands, and cost about US$1. A bug report about invented quotes (issue 529) is partly fixed and still open, and an outside tool that scores forecasts against real outcomes (pull request 813) has had no review since September 15.
Read More: Research on why teams of AI agents often fail to beat a single agent and Simile, a startup that sells AI models of real customer groups to large companies
Sources:
- MiroFish README (GitHub)
- 36Kr: student builds MiroFish in 10 days, Shanda commits 30 million yuan
- WPP research: MiroFish, is swarm intelligence worth the cloud bill?
- Simile: Announcing our Series B
- Historical backtesting framework (GitHub pull request 813)
Disclaimer: For information only. Accuracy or completeness not guaranteed. Illegal use prohibited. Not professional advice or solicitation. Read more: /terms-of-service
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Citation
@misc{kabui2026,
author = {{Kabui, Charles}},
title = {MiroFish: {A} {Free} {Student-Built} {Tool} {That}
{Simulates} {AI} {Crowds} {Reacting} to {News}},
date = {2026-11-09},
url = {https://toknow.ai/posts/mirofish-swarm-prediction-engine-startup-lessons/},
langid = {en-GB}
}