No overload for method 'fireBullet' takes 0 arguments

In a game I'm making you can shoot lasers. I want them to go towards where the mouse is but I keep getting the error in the title. Here is my script:

void Update () { if (Input.GetKeyDown("space")) { GetComponent().Play(); fireBullet();

         //GameObject bullet01 = (GameObject)Instantiate(PlayerBulletGO);
         //bullet01.transform.position = BulletPosition01.transform.position;
     }

     float x = Input.GetAxisRaw("Horizontal");
     float y = Input.GetAxisRaw("Vertical");

     Vector2 direction = new Vector2(x, y).normalized;
     Move (direction, x);
 }

 void Move (Vector2 direction, float move)
 {
     Vector2 min = Camera.main.ViewportToWorldPoint (new Vector2(0, 0));
     Vector2 max = Camera.main.ViewportToWorldPoint (new Vector2(1, 1));

     max.x = max.x - 0.285f;
     min.x = min.x + 0.285f;

     max.y = max.y - 0.600f;
     min.y = min.y + 0.200f;

     Vector2 pos = transform.position;

     pos += direction * speed * Time.deltaTime;

     pos.x = Mathf.Clamp (pos.x, min.x, max.x);
     pos.y = Mathf.Clamp(pos.y, min.y, max.y);

     transform.position = pos;

     if (move > 0 && !m_FacingRight)
     {
         // ... flip the player.
         Flip();
     }
     // Otherwise if the input is moving the player left and the player is facing right...
     else if (move < 0 && m_FacingRight)
     {
         // ... flip the player.
         Flip();
     }
 }

 private void Flip()
 {
     // Switch the way the player is labelled as facing.
     m_FacingRight = !m_FacingRight;

     // Multiply the player's x local scale by -1.
     Vector3 theScale = transform.localScale;
     theScale.x *= -1;
     transform.localScale = theScale;
 }

 void fireBullet(float mousePositionX, float mousePositionY)
 {
     Vector2 position = new Vector2(mousePositionX, mousePositionY);
     position = Camera.main.ScreenToWorldPoint(position);
     GameObject bullet = Instantiate(PlayerBulletGO, transform.position, Quaternion.identity) as GameObject;
     bullet.transform.LookAt(position);
     Debug.Log(position);
     //bullet.rigidbody2D.AddForce(bullet.transform.forward * 10);
     bullet.GetComponent<Rigidbody2D>().AddForce(bullet.transform.forward * 10);
 }

Please help me.