In my experience, and I have a lot when it comes to foods that petshops sell Tetra, Wardleys, Top fin, and most foods that are sold through petstores regularly are just decent foods at best. I used Tetra Koi sticks for many years. Although it is food specifically designed for ponds it's NOT that great of quality. If you were to take two indentical size fish, place them in two tanks the same size and feed them the same amount of food, you will find 30-50% more waste from the fish with one of them versus a premium brand. Also you'll notice that the colors on the fish are bright but not nearly as sharp and vivid in koi that are feed ok quality food versus high grade food. last is the amount of growth versus amount of food that the fish intake. wardleys and top fin, maybe half the growth rate with the same amount of food. tetra more like 25% less. high quality food cost more, but you will get less waste, more growth, and healthier fish that grow faster. To me higher quality food actually brought more easier pond keeping and better looking fish and clearer water in the long run.