--- a/net/minecraft/server/EntityFish.java
+++ b/net/minecraft/server/EntityFish.java
@@ -67,6 +67,7 @@
 
     public void s(boolean flag) {
         this.datawatcher.set(EntityFish.b, Boolean.valueOf(flag));
+        this.persistent = !this.isTypeNotPersistent(); // CraftBukkit - SPIGOT-4106 update persistence
     }
 
     public void b(NBTTagCompound nbttagcompound) {