spawn in specific areas only

I am trying to make this prefab spawn in certain areas only,

yes I want random spawns in the specific area but only 2 per

every 4 seconds so criteria 1 random location spawns in the specific spawn area 2 only about 2 per every 4 seconds after the others have died

or left scene

when I play this it freezes my scene I read, I have to setup a empty gameobject area and use it

as a spawn point but even when I test this code it freezes and or spawns many

this is a 2d game and c#

 using UnityEngine;
 using System.Collections;
 public class fish2 : MonoBehaviour {
     
     private Vector3 spawnPosition = new Vector3 (-4.62f, 2, 0);
     private Vector3 position1 = new Vector3 (2, 2, 0);
     public GameObject fishPrefab; 
     public float Speed;
 
     void Start()
     {
         // To Spawn:
         GameObject fish = Instantiate (fishPrefab, spawnPosition, Quaternion.identity) as GameObject;
     }
     InvokeRepeating("Launchfish", 2.0f, 6.0f);
 
         // To move:
         fish. transform.position = Vector3.MoveTowards(fish.transform.position, position1, Speed * Time.deltaTime);
     }
 void Launchfish () {
     Rigidbody2D instance = Instantiate(fishPrefab);
     instance.velocity = Random.insideUnitSphere * 5;
 // Starting in 2 seconds.
 // a projectile will be launched every 0.3 seconds
     //public Rigidbody2D projectile;
     //void Start() {
         //InvokeRepeating("LaunchProjectile", 2.0f, 6.0f);
     //}
 /*
     void LaunchProjectile () {
         Rigidbody2D instance = Instantiate(projectile);
         instance.velocity = Random.insideUnitSphere * 5;
     }
 }
    }
   }