i just tested with that settings and it worked ("inverse front" option depends on the orientation of the fish). i don't know if you used control objects or attached the joint to the motion path. if you did it with the joint, i could think that was the problem. try to constrain the skeeton to the control object and use the setting from the screenshot. and don't forget to freeze transformations of the control objects.
Last edited by mickhah; 23-03-2014 at 10:57 PM.