It doesn't mean that those colors should be removed from the food though. Red in brine shrimp and daphnia mean that they are from oxygen poor waters and have developed more hemoglobin. Perhaps their are useful traces of iron in the food. The reds in many foods are also included among the much-coveted carotenes, which do so many good things for your fish's color. People pay extra for them as food additives (Nutra-rosa). Others feed sweet potato baby food to daphnia to improve their fish's colors. For some of us it is a lot cheaper and time saving to buy the flakes.

Aside from banning most commercially brands of prepared foods, our fish would be less healthy and colorful if we had politically correct food colors. And those people who add paprika to their paste foods would win all the shows. ;)

You were on your toes to notice the fish droppings. Now you know to look for "moving droppings. ;) All of us have done a double take at something which fortunately wasn't there. It is just a sign that you are becoming more sophisticated in the aquarist's craft.