There are a lot of brands that are fine for hedgehogs. Some of the Iams and hills products may be okay for a hedgehog, I haven't looked at them in awhile so I'm not sure. I do like the purina brands and the hedgehogs do well on them. I don't think you can say that a specific product line like Iams or Hills or a specific ingredient like fish oil will definitely cause a problem-that is just too broad a statement to makeWhich brands are ok?
Whatever brands you look at, you want a small kibble size, generally around 30% protein and 15% fat or less, avoid preservatives like BHA, BHT and Ethoxyquin.
Usually a mix of 2-3 foods is good because hedgehogs can be picky and you do not want to limit them to one food in case you can't get that food some day. Also a mix of foods will give them a wider variety of nutrition.