I've had 2 over the years. Both ate fairly quickly but only fresh seafood.
Chopped raw shrimp and chopped raw scallops were what they ate initially.
I would also try chopped clams since my current one loves that. The one I have now also loves (hakari jumbo) frozen bloodworms. Next would be Larrys fish frenzy. Doesn't go for PE or typical frozens with nearly as much enthusiasm. Has never eaten dry or nori.
He's starting to pay attention to the LRS foods, but hasn't eaten yet. I have some clams I can offer, I might pick up a couple shrimp tomorrow and try shredding them.