diff --git a/CHANGELOG.md b/CHANGELOG.md
index 7e090af619164dc142b10f44399abb9f8ff4448d..7d47e95ca402dbfdd52130fd7d24a7a5264d7e4a 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -1,6 +1,6 @@
 # Changelog
 
-## [Unreleased]
+## [0.4.0] - 2023-03-24 
 
 ### Added
 
@@ -14,6 +14,7 @@
 - Deprecated `VariableStepGuppyEnv` (use `ConfigurableGuppyEnv` instead, do not use variable step length.)
 - Deprecated `AdaptiveAgent` and related functions (unmaintained and untested)
 - Deprecated built-in Couzin guppies (use `LiveFemaleFemaleConstantSpeedCouzinModel` from `fish_models` instead)
+- Providing `controller_params` is now obligatory for robots that use PID controller simulation
 
 ## [0.3.0] - 2022-10-14
 
@@ -52,4 +53,4 @@
 ### Changed
 
 - Deprecated MXNetGuppy
-- Fixed various small bugs
\ No newline at end of file
+- Fixed various small bugs