diff --git a/src/actor/ac_museum_fish_koi.c_inc b/src/actor/ac_museum_fish_koi.c_inc
index 1a2621a8..24b675d9 100644
--- a/src/actor/ac_museum_fish_koi.c_inc
+++ b/src/actor/ac_museum_fish_koi.c_inc
@@ -1,6 +1,29 @@
-
-void mfish_koi_tail_anim_set() {
-    return;
+void mfish_koi_tail_anim_set(MUSEUM_FISH_PRIVATE_DATA* actor, s32 r4) {
+    f32 temp;
+    if (r4 == 0) {
+        actor->_640 = (int)(6.0f * fqrand()) + 25;
+        //! BUG: fqrand2 called without being used
+        // Maybe some kind of min-max macro, where we're multiplying fqrand2 by 0 (temp - temp),
+        // but including fqrand2() directly in the equation below generates extra fmuls instr for some reason.
+        // The only way around it we found was to call it like this.
+        fqrand2();
+        temp = 6.5f;
+        actor->_5AC.x = temp + (f32)(temp - temp);
+    } else if (r4 == 1) {
+        if (actor->_640 == 0) {
+            actor->_640 = (int)(4.0f * fqrand()) + 20;
+            //! BUG: fqrand2 called without being used (see context above)
+            fqrand2();
+            temp = 5.0f;
+            actor->_5AC.x = temp + (f32)(temp - temp);
+        }
+    } else if (actor->_640 == 0) {
+        actor->_640 = (int)(6.0f * fqrand()) + 45;
+        //! BUG: fqrand2 called without being used (see context above)
+        fqrand2();
+        temp = 1.0f;
+        actor->_5AC.x = temp + (f32)(temp - temp);
+    }
 }
 
 void mfish_koi_move_smooth() {
@@ -9,7 +32,14 @@ void mfish_koi_move_smooth() {
 
 void mfish_koi_ct(MUSEUM_FISH_PRIVATE_DATA* actor, GAME* gamex) {
     GAME_PLAY* game = (GAME_PLAY*)gamex;
-    return;
+
+    mfish_onefish_ct(actor, gamex);
+    mfish_base_ct(actor, gamex);
+
+    actor->_34 = mfish_koi_normal_process;
+    actor->_5E8 = actor->init_data._10;
+    actor->_5AC.z = 1.0f;
+    actor->_624 = 9;
 }
 
 void mfish_koi_dummy_process_init() {