Mercury is a valid concern when introducing fish, including tuna, to babies. Opt for varieties of tuna that are lower in mercury, such as light canned tuna. This type of tuna generally contains lower levels of mercury compared to albacore (white) tuna.
Additionally, you can refer to guidelines from reputable health organisations for safe fish consumption recommendations based on your baby's age and weight. As a precaution, it's wise to limit the frequency of tuna consumption and offer a variety of fish options to minimise mercury exposure.