Many studies have been done showing great growth and breeding potential from fish being fed earthworms. This flake is especially loved by discus.Zeigler Specialty flake 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 excreted 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