Move object on curve with same angle

I am trying to move my object on curve path that is simple animation not any physics implementation.

I have already working of object on curve based path but can't able to find same movement angle.

For movement of game object I used iTween and code for that are represented as under.

 iTween.MoveTo(gameObject,iTween.Hash("path",iTweenPath.GetPath("FishDeath"),"time",2f));

But how to apply angle correct angle to game object not static rotation angle 0??

Following image represent my path

At present movement on that path is possible but I can't able to calculate angle for game object.