diff --git a/pkgs/shells/fish/plugins/clownfish.nix b/pkgs/shells/fish/plugins/clownfish.nix
new file mode 100644
index 000000000000..cd5c997d3114
--- /dev/null
+++ b/pkgs/shells/fish/plugins/clownfish.nix
@@ -0,0 +1,20 @@
+{ lib, buildFishPlugin, fetchFromGitHub }:
+
+buildFishPlugin {
+  pname = "clownfish";
+  version = "unstable-2021-01-17";
+
+  src = fetchFromGitHub {
+    owner = "IlanCosman";
+    repo = "clownfish";
+    rev = "a0db28d8280d05561b8f48c0465480725feeca4c";
+    sha256 = "04xvikyrdm6yxh588vbpwvm04fas76pa7sigsaqrip7yh021xxab";
+  };
+
+  meta = with lib; {
+    description = "Fish function to mock the behaviour of commands";
+    homepage = "https://github.com/IlanCosman/clownfish";
+    license = licenses.mit;
+    maintainers = with maintainers; [ pacien ];
+  };
+}
diff --git a/pkgs/shells/fish/plugins/default.nix b/pkgs/shells/fish/plugins/default.nix
index e543d49516a8..9d7043c97921 100644
--- a/pkgs/shells/fish/plugins/default.nix
+++ b/pkgs/shells/fish/plugins/default.nix
@@ -4,6 +4,8 @@ lib.makeScope newScope (self: with self; {
 
   buildFishPlugin = callPackage ./build-fish-plugin.nix { };
 
+  clownfish = callPackage ./clownfish.nix { };
+
   fishtape = callPackage ./fishtape.nix { };
 
   foreign-env = callPackage ./foreign-env { };