I agree with a comment in another recent thread that talking fish food is almost as bad as talking religion and politics sometimes, but I'll just add my personal review, take it for what it's worth--
Some years ago I did a good bit of head to head testing of Hikari, NLS, and several other foods. The difference between Hikari and a couple of others that were better, including NLS, was apparent in a short time, not just in the color of the fish but also appetite of some of my fish that had been finicky eaters-- between the two, NLS just produced better results than Hikari in my test.
In fact, why I mention Hikari and what initially started me doing a lot of food testing was this-- I could no longer find the food I'd been using previously, so I switched to Hikari only because it was the most expensive food available locally and I was trying to buy the best. But I was discontent with the fact that I'd buy some beautiful fish online and after a couple of months they didn't look as good as when I first got them (I no longer have this problem, fish now look just as good or better after I've had them a while). Meanwhile I had started reading about fish food and nutrition, which is when I decided to test foods out for myself, including side by side tanks, fry from same spawn, growing them out to breeding age, etc.
I'm not trashing Hikari and I'm not saying NLS is the holy grail of all fish food; I really have no particular food axe to grind here. Of all the foods I tested Hikari was basically in the middle, certainly better than some, but not one of the top two or three foods I tested, which included NLS. The common denominator difference between the best two or three foods I tested and most everything else was the number of grains, starches, glutens, etc. in the ingredients; the better results came from foods with less of them ime. The simple eye test of looking at the ingredients list on the label correlated pretty consistently with what I saw with my fish.
Some years ago I did a good bit of head to head testing of Hikari, NLS, and several other foods. The difference between Hikari and a couple of others that were better, including NLS, was apparent in a short time, not just in the color of the fish but also appetite of some of my fish that had been finicky eaters-- between the two, NLS just produced better results than Hikari in my test.
In fact, why I mention Hikari and what initially started me doing a lot of food testing was this-- I could no longer find the food I'd been using previously, so I switched to Hikari only because it was the most expensive food available locally and I was trying to buy the best. But I was discontent with the fact that I'd buy some beautiful fish online and after a couple of months they didn't look as good as when I first got them (I no longer have this problem, fish now look just as good or better after I've had them a while). Meanwhile I had started reading about fish food and nutrition, which is when I decided to test foods out for myself, including side by side tanks, fry from same spawn, growing them out to breeding age, etc.
I'm not trashing Hikari and I'm not saying NLS is the holy grail of all fish food; I really have no particular food axe to grind here. Of all the foods I tested Hikari was basically in the middle, certainly better than some, but not one of the top two or three foods I tested, which included NLS. The common denominator difference between the best two or three foods I tested and most everything else was the number of grains, starches, glutens, etc. in the ingredients; the better results came from foods with less of them ime. The simple eye test of looking at the ingredients list on the label correlated pretty consistently with what I saw with my fish.