When pregnant, you should also limit the amount of tuna you eat to:
- no more than two tuna steaks a week (about 140g cooked or 170g raw each), or
- four medium-sized cans of tuna a week (about 140g when drained)
This is because tuna contains more mercury than other types of fish. The amount of mercury we get from food isn't harmful for most people, but if you take in high levels of mercury when you're pregnant, this could affect your baby's developing nervous system.
Children, pregnant women and women who are trying to get pregnant should not eat shark, swordfish or marlin. This is because they contain more mercury than other fish.
Other adults should have no more than one portion of shark, swordfish or marlin per week.
The FSA also has advice on the amounts of fish that should be eaten on the basis of other pollutants they may contain. This can be found on the NHS Choices website via the ‘External sites’ link on this page.