When my first one was being stubborn, it made a difference to COMPLETELY remove all food, wait a number of hours and then put the food back in. Aro's stalk their prey, give him 20 minuts, if show's any interest, let it floow the crickets. If he show no interest at all after 10 mintes or so, remove them and wait again. Taking the food all the way away made mine think twice about saying no, it worked. With a bigger fish, I'd say try it every 6-8 hrs, with yours I'd try maybe 3-4 hrs.
If it has eaten even a few crickets over the past few days, or anything for that matter, then it is getting nutrition.
How's it going this morning?