Rats have specific nutrional and dietary needs, so they can't be fed generic small animal food (no animal should be fed that - every type of animal has different needs, there's no catchall food). You might find Mazuri lab blocks with low protein (I've never fed this, but heard some Mazuri has 23% protein which is too high, but some has I think 16% which is okay). There's a post not far down about Oxbow Regal Rat which some people have seen in stores, which would be good if you can find it. Other than that, you're not going to find anything suitable in a store. If you can order online, get Harlan Teklad lab blocks. If you can't do that, and can't find Mazuri or Regal Rat in the store, you'll have to feed a good quality, low-protein dog food with Suebee's mix.