Vitamins and minerals
Vitamin and mineral content varies from fish to fish
The amount of vitamins and minerals is species-specific and can also vary seasonally. In general, fish meat is a good source of the B vitamins and also of the A and D vitamins in the case of fatty species. Some freshwater species such as carp have high thiaminase activity so the thiamine content in these species is usually low. As for minerals, fish meat is regarded as a valuable source of calcium and phosphorus in particular but also of iron, copper and selenium. Saltwater fish have a high content of iodine.
Vitamin content in fish is comparable to that of mammals except in the case of A and D vitamins which are found in large amounts in the meat of fatty species and in abundance in the liver of species such as cod and halibut. It should be noted that the sodium content of fish meat is relatively low which makes it suitable for low-sodium diets.
In aquacultured fish, the contents of vitamins and minerals reflect the composition of the corresponding components in the fish feed, although the observed data should be interpreted with great caution. In order to protect the n-3 polyunsaturated fatty acids, important both for fish and human health, vitamin E may be added to the fish feed as an antioxidant. It has been shown that the resulting level of vitamin E in the fish tissue corresponds to the concentration in the feed.