Fish Wandering script

using System.Collections;
using System.Collections.Generic;
using UnityEngine;
using DG.Tweening;

public class FishWander : MonoBehaviour
{
    //Move vars
    [Range(1.0f, 30.0f)]
    public float deviateMaxAngle = 10.0f;
    public float speed;
    [Range(1.0f, 60.0f)]
    public float seekDistance = 40.0f;
    private Vector3 destination;
    public float bumpDistance = 1f;
    public float turnSpeed = 0.15f;
    private bool needsMove = true;
    Sequence movementSequence;
    private bool hasCollided = false;

    //Flip Flap vars
    public float swimSpeed;
    public GameObject firstBone;
    private bool flipFlapFinished = true;

    //Idle state vars
    public Vector2 waitSecondsRandomRange;
    private float waitSeconds;

    void Update()
    {
        if(needsMove){
            MoveToDestination();
        }

        if(flipFlapFinished)
        {
            FlipFlap();
        }

        if(!hasCollided){
            TryToCollide();
        }
    }

    void TryToCollide()
    {
            RaycastHit hit;
            if(Physics.Raycast(transform.position, transform.forward, out hit, bumpDistance))
            {
                Debug.DrawRay(transform.position, transform.forward * hit.distance, Color.white);
                hasCollided = true;
                movementSequence.Pause();
                MoveToRadicalDestination();
            }
    }

    void MoveToDestination()
    {
        needsMove = false;
        GetDestination();
        movementSequence = DOTween.Sequence();
        movementSequence
        .Append(transform.DOLookAt(destination, turnSpeed).SetEase(Ease.Linear))
        .Append(transform.DOMove(destination, speed).SetEase(Ease.Linear))
        .AppendCallback(() =>
            {
                StartCoroutine(StandIdle());
            }
        )
        .SetAutoKill(true);
    }

    void MoveToRadicalDestination()
    {
        needsMove = false;
        GetRadicalDestination();
        movementSequence = DOTween.Sequence();
        movementSequence
        .Append(transform.DOLookAt(destination, turnSpeed).SetEase(Ease.Linear))
        .Append(transform.DOMove(destination, speed).SetEase(Ease.Linear))
        .AppendCallback(() =>
            {
                hasCollided = false;
                StartCoroutine(StandIdle());
            }
        )
        .SetAutoKill(true);
    }

    void GetDestination()
    {
        Vector3 testPosition = (transform.position + (transform.forward * seekDistance)) +
            new Vector3(
                Random.Range(deviateMaxAngle*-1, deviateMaxAngle),
                Random.Range(deviateMaxAngle*-1, deviateMaxAngle),
                Random.Range(deviateMaxAngle*-1, deviateMaxAngle)
                );
        destination = testPosition;
    }

    void GetRadicalDestination()
    {
        Debug.Log("Goes to Radical Destination");
        Vector3 testPosition = (transform.position + (transform.forward * -1 * seekDistance));
        destination = testPosition;
    }

    void FlipFlap()
    {
        flipFlapFinished = false;
        firstBone.transform.DOLocalRotate(new Vector3(0,0,12), swimSpeed, RotateMode.FastBeyond360).SetEase(Ease.InOutSine).SetRelative(true).SetLoops(2, LoopType.Yoyo)
        .OnComplete(()=>{
            flipFlapFinished = true;
        }).SetAutoKill(true);
    }

    IEnumerator StandIdle()
    {
        swimSpeed*=2f;
        waitSeconds = Random.Range(waitSecondsRandomRange.x, waitSecondsRandomRange.y);
        yield return new WaitForSeconds(waitSeconds);
        swimSpeed*=0.5f;
        needsMove = true;
    }
}