Plankton/Krill/Spirulina Flake contains a blend of Plankton, Krill, and Spirulina which are known to enhance natural coloration in tropical fish. Zeigler Specialty flakes are nutrionally balanced all-purpose diets for all types of omnivirous freshwater and Marine species who feed on invertebrates in the wild. These diets utilize highly digestable marine proteins to increase both palatability and digestibility, while minimizing ecreted wastes.increased levels of stable Vitamin C and brewers yeast are included in these diets to promote healthy gill, fin, and tissue development. Info from Zeigler