GVG-Iodine-rich flake food with tasty morsels for all saltwater fish. Saltwater fish need more iodine and other minerals than freshwater fish. sera GVG-mix marin consists of 80% special flakes made from marine algae, ground krill and plankton. 20% are FD bloodworms, daphnia and Artemia brine shrimp. sera GVG-mix marinis excellent for providing marine fish with iodine and other essential minerals as well as prevention of thyroid gland diseases.