The NRC requirements for aquatic animals are dietary vitamin levels needed to prevent overt clinical deficiency signs. Optimal allowances compensate for stress factors on the animal and on the feed, thus ensuring that vitamin fortification does not limit performance and health. These guidelines are based on extensive university and industry research, published requirements, field experience, and characteristics, such as stability and uniformity of the commercial product forms used to supplement vitamins in premixes, base mixes and complete feeds.
These guidelines are ranges to try to accommodate the numerous factors that influence the vitamin requirements of animals, including the wide variations in commercial feed manufacturing practices and the stresses involved in modern production.
Yet the listed vitamin levels are only guidelines and should be adapted to local conditions. These guidelines may not meet the requirements of the animal in all cases, for example during restricted feeding. In all cases, national feed legislation must be followed.