Could be pickiness from the store. Ludendorff would not eat anything BUT omega pellets since I brought him home. It's only recently that I'm able to get him to eat bloodworms! He was always so wary of them.
Now my fish have Omega One, Tetra Crumbles, Attison's Pro, and when I see my mom next I'll swap some of my food for hers (Aqueon) for variety! Plus they get frozen bloodworms, and as they say, "Variety is the Spice of Life!!"
How Ludey warmed up to different food? Fast him for a day after feeding what he likes and offer only the other food. Sounds cruel but he will eat it and then he'll have a variety of food! ^.^