A small mod that fixes fish stop moving entirely MC-182763

Support with Minecraft 1.17.x-1.20.x for Fabric (Quilt maybe?)/Forge

How it works

The fish has an AI Goal that scans for the nearest fish, which will randomly select a leader and followers. Then it will let the follower fish follow the leader.

This mod applies bug fix to FollowFlockLeaderGoal by checking the nearest fish if it is a leader or not. If not, it will add into the follower list.

If leader gets added into the follower list. A Fish Leader will stop and not go to anywhere along with their followers (Forever!). Unless you hit them or switch gamemode to survival and swim near them.

For Minecraft Bug Report, see: https://bugs.mojang.com/browse/MC-182763

Another fix in this mod is:

  • Check entity predicate by using EntitySelector.NO_CREATIVE_OR_SPECTATOR instead of EntitySelector.NO_SPECTATORS in avoid entity goal.
  • Set checkNoActionTime to false in FishSwimGoal to fix fish getting stuck at the current position
  • Decreased schoolSize from leader fish if the follower fish is getting killed.

Performance Impact

This mod doesn't improve any game performance, or it has very minor impact, especially for fish. See FishNoStuck#1


  • Install Fabric Loader/MinecraftForge
  • Copy mod into mods folder


I was working on Fish of Thieves by looking at FollowFlockLeaderGoal and figure it out how it works, then convert it to use Brain system.

By display debug data above an entity.

Then I realize something wrong. A fish with schoolSize=8 has property isFollower=true and has a leader. Which it should not be possible. So that's the beginning of this mod.