Sera GVG Mix Marin is an 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 Marin is excellent for providing marine fish with iodine and other essential minerals as well as prevention of thyroid gland diseases.