If he's fat and healthy, you can fast him for a while. Don't feed him for a few days, then start offering tempting things like the shrimp or even bloodworms. Once you get him eating stuff like that, you can try soaking the pellets in the juice of whatever his favorite food is to try and make them more appealing. Some are more stubborn than others and refuse to ever take pellets. I have a sveni that I found at a pet store and even though it was young and in good shape, it still proved impossible to convert. My Saxatilis was the exact opposite -- he ate pellets within a couple weeks and now he's the first one at the lid during feeding time. It may just come down to each individual pike's willingness.