Many fish food products will list grains and fillers in the first 3 ingredients. I'd avoid those.
"fish meal" and "shrimp meal" might contain grains and fillers as well, either legally or not.
It would be better to look at the analysis, and check available protein and vitamins.
You can safely feed your fish Tetra and Hikari. Millions of aquarists have done so for decades without problems. Sure they are overpriced, every large corporation has a huge overhead you're paying for.
There is another problem though that Brand Y or Z is not going to fix.
All these foods are processed. It's like living on instant noodles each day.
So what the most dedicated aquarists and private breeders do is either solely feed their fish (talking about general small community fish here) live foods or frozen foods, or they make their own flakes and pellets, from fresh ingredients, up to the standard that they themselves can eat it too for dinner... it has to be palatable for humans as well. No kidding.
Dry fish food is a convenience product just like dry cat food. Use what you got as a staple and vary a couple of times a week with frozen or live foods. It's a middle of the road approach but the fish will be fine.
