As we are talking about pet food in general let me toss out what I have found about dog food. Look at the ingredients lists. Meat (not meal) of some type should be the first ingredient. There should be no corn, wheat or by-products. Innova, Wellness, Orijen & Merrick are a few of the good brands out there. Just as with humans the better the food (nutrition) the better the health. While people can live on junk food for a time, their health suffers. Same with dogs, they can live on the cheaper brands of dog food BUT A low cost poor quality food that will have you asking questions like,"why does my dogs breath smell so bad?" "why does my dog have a bad body odor?" "what can i give my dog to give it a shiny coat?" "why does my dog scratch all the time?" That's what cheap food can do for your dog. Now a premium quality food has the nutrients a dog needs without the corn and wheat fillers that cause problems and they don't have by products (want to feed your dog cancerous tissue?) Premium quality foods come at a higher price but they are worth it.
I am trying to figure out how this works to answer questions.
You mentioned more poop with poor quality fish food. It is the same with dog food. If you feed the better dog foods you get a smaller, firmer, less stinky stool.
Like you I do not stick to just one food. My guy gets a blend of a few of the premium quality foods. I buy Merrick, Wellness, Blue and Orijen and mix them. Yes, there is a big difference in feeding a dog food with "Chicken" as the first ingredient than feeding one with "Corn" as the first ingredient.
