Freezing Prefab or deactivating its script in another?

Okay so I have this fish prefab with a waypoints movement script attached to it. I tried everything from simple fishdist = 0; to disableFish.SetActive(false); I have no other clue left on how to freeze the prefab in place. When I use any of these it continues to move. Am I doing something wrong or iterating it incorrectly?

 void Update ()
 {
             if (Physics.Raycast (ray, out hit, maxCastDist, waterMask))
             if (hit.collider != null) {

                 float dist = Vector3.Distance (hit.point, target.position);
                 Debug.Log (dist);

                 Instantiate (Float, hit.point, Quaternion.identity);
                 if (dist < fishDist) {

                     // stop fish in place 
                     //fishdist = 0;
                     disableFish.SetActive(false);
                     StartCoroutine (fishWaiter ()); // delay random when fish will be "retrieved"

                 } 

             }
         }
     }
 }

 


 IEnumerator fishWaiter ()
 {
     FishLoader.SetActive (true);

     //disableFish.GetComponent<Waypoints> ().enabled = false;


     float waitFishtime = Mathf.Clamp01 (5f);

     FishSlider.value = waitFishtime;

     Debug.Log ("Timer Started");
     yield return new WaitForSeconds (waitFishtime);
     print ("I waited" + waitFishtime + "Sec");

     Destroy (GameObject.FindWithTag ("Fish"));

     FishSlider.value = 0f;

 
     print ("You Caught The Fish!");
     ScoreManager.score += scoreValue;
     AchievementManager.Instance.EarnAchievment (achievmentName);
 }

}