Minecraft's underwater world has always felt a bit static — fish swim around aimlessly, rarely behaving like actual schools of fish. Boids Mod changes that entirely by replacing vanilla fish AI with a proper boids simulation, the same algorithmic approach used in CGI films to recreate realistic flocking behavior. The result is fish that dynamically separate, align, and regroup just like real schools do in nature. With over 2.6 million downloads and active development by Tomate0613, this Fabric-side tweak has become one of the most popular ambient mods for turning oceans and rivers into something worth watching.
Key Features
- Separation behavior — Fish actively steer away from nearby flockmates to avoid crowding, preventing the unnatural clumping you see with vanilla AI.
- Alignment behavior — Each fish adjusts its heading to match the average direction of its neighbors, creating smooth coordinated movement across the school.
- Cohesion behavior — Fish steer toward the center of mass of their local group, keeping the school together as a unified formation rather than scattering randomly.
- Open source (MIT license) — Fully transparent codebase hosted on GitHub, allowing anyone to inspect, modify, or contribute to the mod.
Screenshots
How to Install
- Download and install Fabric Loader for your Minecraft version from the official Fabric website.
- Download Fabric API and place the .jar file into your
modsfolder. - Download the Boids Mod .jar file matching your Minecraft version.
- Place the Boids Mod .jar into your
.minecraft/modsfolder. - Launch Minecraft using the Fabric profile and enjoy realistic fish flocking.
Requirements
| Requirement | Details |
|---|---|
| Mod Loader | Fabric |
| Dependencies | Fabric Loader, Fabric API |
| Minecraft Versions | 1.21.11, 1.21.10, 1.21.9, 1.21.8, 1.21.7, 1.21.6, 1.21.5, 1.21.4, 1.21.1, 1.20.6, 1.20.4 |
Pros & Cons
Pros
- Dramatically improves underwater immersion with realistic flocking behavior
- Open source under MIT license — fully transparent and community-driven
- Broad version support from 1.20.4 through 1.21.11
- Actively maintained with regular updates and bug fixes
- The mod appears to be lightweight since it only modifies fish AI behavior
Cons
- Fabric-only — no Forge or NeoForge support available
- Requires Fabric API as an additional dependency
- Limited to fish behavior — does not affect other mob flocking like bats or bees
Download
Always download mods from official sources to stay safe.
What's New
- Fixed issue #23 — fish were being grouped incorrectly, causing unnatural school formations.
- Updated FMJ (Fabric Mod JSON) for improved mod metadata and compatibility.
- Overall stability improvements to the flocking simulation.
FAQ
Does Boids Mod work with other fish mods?
Boids Mod replaces the vanilla fish flocking AI, so it may conflict with other mods that also modify fish behavior. Mods that only add new fish species without changing AI should generally work alongside it.
Which fish are affected by Boids Mod?
The mod targets vanilla flocking fish — cod, salmon, tropical fish, and other schooling fish in Minecraft. It replaces their default movement patterns with the boids simulation for more realistic group behavior.
Is Boids Mod available for Forge or NeoForge?
Currently, Boids Mod is only available for Fabric and requires both Fabric Loader and Fabric API. There is no Forge or NeoForge version at this time.
![[Let's Do] Meadow Mod (1.21.1) - thumbnail](http://mcinside.com/wp-content/uploads/2026/04/thumbnail-64-52x52.webp)
![Not Enough Recipe Book [NERB] Mod (1.21.11) - thumbnail](http://mcinside.com/wp-content/uploads/2026/04/thumbnail-63-52x52.webp)
