Nutritive supplements are often used in food production in order to prolong shelf life of the product or to enhance some particular product properties. These supplements can be classified in two categories: natural and artificial. Fishing industry usually uses supplements to slow down growth of microorganisms, as well as to prevent oxidation of lipids, which can have a great impact on the quality of the product. Current trends in nutrition are promoting usage of natural supplements, since artificial ones may have a negative impact on human health. The most common natural additives used in fishing industry are various herbs and herbal extracts, which improve the product's aroma and have anti-oxidant and antimicrobial effect. In order to ensure proper usage of supplements in dietary products and to prevent allergic reactions, all supplements must be categorised and marked by a special E number. Furthermore, usage of these supplements is strictly regulated by laws. Hence, it is very important that each product has a valid and accurate product declaration to avoid any negative impact on the end consumers.