Ok I do have to disagree on the tuna not working part, I have the utmost respect for the advice Kaorte gives from what I've seen on the forum, but Ive seen tuna scenting work first hand on one of my finicky eaters. I also know that BHB uses this method for some of theirs and has success with it.
I started with a fire that wouldnt eat at all, dropped a live mouse in with some canned tuna for alittle while, she struck immediately, once it was introduced into her tub. I also got her to switch to F/T this way by scenting a few live for consecutive feedings, then scenting a f/t and offering it on feeding day. No hesitation were before she had no interest in f/t.