I thought that you suggested reduced feeding to lower nitrates. I believe that you presumed that feeding 4 times a day was overfeeding without really knowing how much was fed at each feeding. And I think
@Agus (when s/he spoke of feeding 10x daily) was referring to growing out perhaps hundreds of fish in breeder grow out ponds. Something few hobbyists have experience with. As the water boils in these ponds during feeding, individual fish only typically get a small amount of food...and that's if they're quick.
There are some that often recommend withholding food one or more days a week to 'clean the fish out' presuming it makes them healthier. (I think the jury is still out on that one). I do know it's recommended to withhold food a day or two before shipments or auctions to keep waste out of the bag, but that's a different matter to better ensure survival.