Zeigler Koi Fancier contains spirulina and other natural marine ingredients to enhance the vibrant colors of your fish. The diet is formulated with stable vitamin C and brewers yeast to help improve immune function and promote healthy tissue development. Higher levels of marine protein sources are incorporated to maximize palatability and digestibility. Koi Fancier is also supplemented with Vpak, an all-natural additive, to help increase resistance to diseases. As with all Zeigler diets, Koi Fancier is manufactured according to ISO-9001 guidelines.