The smaller the bag, the more easily the flake is broken during packaging, and shipping, so larger sizes are better for those with large fish. Multiple-color flakes are mixed and the mixing process breaks the flakes into smaller pieces. Therefore, single-color flakes may be a bit larger on average and some larger fish may prefer the bigger flakes. This is just a general guideline. Fish accustomed to smaller flakes will continue to eat them even when the fish themselves are very large. Keep in mind this is a bulk product in a soft package and every bag will have some small flakes and rough handling from the carrier can cause breakage. Every bag will have flake of various sizes and it will range from very small to larger flakes.
We use black foil bags (except on BULK items) which are the best for keeping out damaging oxygen and light, making for the freshest food possible. In addition, we turn our stock over every 4-6 weeks. Food never gets old sitting on a shelf here.