When's safe to eat tined tuna?? 🐟🐟🐟

Yasmin
Have read everywhere that tuna or fish that contains a lot of mercury isn't safe during pregnancy. Now, would this just be the first trimester or all the way through? I really fancy some and am making a conscious effort not to put on any more weight πŸ˜‚πŸ˜‚. Hope someone can help 😁