food standards agency says this about eating oily fish (fresh tuna counts as oily fish but tinned tuna doesnt):
Even though eating oily fish has a number of benefits, there are limits to the amount we should eat.
Girls and women who might have a baby one day shouldnt eat more than two portions of oily fish a week. A portion is 140g. In general, this advice also applies to women who are pregnant or breastfeeding.
Women who arent going to get pregnant in the future, boys and men can eat up to four portions a week.
Yes of it's cooked well but given that the only way to eat tuna where It is actually edible is to have it rare. Children really are meant to have food cooked well done. Having said that I got fed up of dd leaving meat and tuna so decided to cook it how it's meant to be eaten as if was a waste otherwise and when dd2 came along she had no choice but to conform