Living Reefs

Coral reefs that grow, bleach and recover on their own.

In vanilla Minecraft a coral reef is a painting: coral only grows from bone meal and only ever dies. Living Reefs makes reefs live. Coral spreads its own kind across the sea floor, turns white next to a magma vent, and comes back once the heat is gone. Restore a dead reef, farm one, or just watch it grow while you build.

Server-side only. Players join with a vanilla client.

Features

• Coral spreads its own kind into nearby still water: plants and fans on sand, wall fans on the side of a block, and new coral blocks that build the reef up to three high.
• Bleaching: coral next to magma or lava, or in frozen water, turns into its dead, white twin.
• Recovery: remove the heat and thriving coral slowly takes back dead coral of its own kind right next to it. Plant living fragments next to a dead reef to bring it back.
• What a reef likes: warm ocean water, light (sea pickles light deep reefs), tropical fish and sea pickles nearby (growth x1.5 each), and an active conduit (x2), which also makes any water a reef and shelters coral from bleaching.
• /reef check tells you whether a coral is thriving, dormant or stressed, and why.
• Never too dense: new coral only fills still water on sand, gravel, stone, clay or coral in warm oceans, never replaces a block, keeps two blocks of water above it, and never goes where 14 coral are already within two blocks. Over many hours near players a reef does creep slowly across warm ocean floor; one game rule turns growth off.
• Safe for your builds: coral outside warm oceans just stays as it is (unless you build an active conduit near it), dry dead coral (decoration) is never touched, and nothing is saved on the side: every change is a vanilla coral block.
• Light on the server: runs on vanilla random ticks, so only near players, at random_tick_speed, and never loads chunks. A warm ocean reef of 8,192 coral costs about 0.1 ms per tick at default speed.

What it looks like

Real output of /reef check from the screenshots below:

Brain Coral Block at -591 51 2649 is thriving
  ✔ warm reef water
  ✔ light 10, needs 1
  + 5 tropical fish nearby (x1.5)
  1 open spot to spread to
  Tries to spread about every 19 min while players are near

Next to a magma vent:

Brain Coral at -592 51 2650 is stressed
  ✘ magma or lava within 2 blocks
  Bleaches in about 5 min if nothing changes

In game it is colour coded: green when thriving, yellow when dormant, red when stressed.

Gallery

Every screenshot is a real capture from the game client, made by the mod's own capture test. The time-lapse is sped up with random_tick_speed.

How it works

Living coral gets random ticks, like grass and crops. Most ticks do nothing; now and then a coral reads its surroundings:

At default speed a thriving coral tries to spread about every half hour, only near players.

Commands

/livingreefs and the short alias /reef are the same command.

Game rules: livingreefs:coral_growth and livingreefs:coral_bleaching (both true).

For server owners

• Permissions: with a permissions mod such as LuckPerms, grant livingreefs.use and livingreefs.admin. Without one, operator level 3 is needed to reload.
• Config: config/livingreefs.json holds every chance, radius, cap and boost. Out-of-range values are clamped with a warning; a broken file is reported and left untouched.
• Datapack tags: livingreefs:reef_waters and frozen_waters (biomes), reef_substrate and reef_heat_sources (blocks).
• Compatibility: tested with Lithium. Modded coral that extends the vanilla coral blocks and is named like vanilla coral works automatically.

Install

Needs Minecraft 26.3, Fabric Loader 0.19.5 or newer, Fabric API and Java 25.

• Server: put the Living Reefs jar and Fabric API in the server's mods/ folder.
• Singleplayer: install Fabric Loader for 26.3, then put both jars in .minecraft/mods.

Links

• Source, issues and changelog: github.com/razekteixeira/living-reefs
• Project page: razekteixeira.github.io/living-reefs

Open source under the Apache License 2.0.

NOT AN OFFICIAL MINECRAFT PRODUCT. NOT APPROVED BY OR ASSOCIATED WITH MOJANG OR MICROSOFT.