Fish started in the heart of the Hibs defence and played the full 90 minutes, as the home side went 3-0 up within the first half, through two goals from Josh Campbell and another from Elie Youan.
Kevin Nisbet made it four on 73 minutes, before Aberdeen centre-back Liam Scales was dismissed for a second bookable offence.
Campbell completed his hat-trick in the 88th, before Fish rose high at the back post to power an injury-time free-kick beyond the grasp of Joe Lewis, notching his first goal since arriving on loan in September.
Will Fish makes it ud835udde6ud835udddcud835uddeb ud83dude0d
Drop a u2764 for @_wfish!