You should be able to get any pike onto prepared foods, be it shrimp, mysis, pellets, stuff like that. All you need is a good dose of patience and determination. Haven't kept a pike yet that I wasn't able to change over to prepared foods. I'm sure there are tons here that have much the same success story. Its just healthier for them to get a varied diet, with as much nutrients as possible. Gut loading is probably what you are gonna have to do. Puree the food, suck it up in a seringe, and inject it into the feeders. kinda weird doing it, but you gotta do what you gotta do.
What quality is of utmost importance, as it was stated. Definately keep your water as clean as possible. Another thing noted is that pikes (or cichlids in general) kept in HARD water seem to be less prone to HITH. I mean, how many african cichlids do you know of that have HITH? I've always had hard water, here and in Nebraska, kinda sucks for breeding, but it is great for keeping the HITH away.