I guess it depends on what you consider low mercury levels. Since mercury is a bio-accumulated toxin, the easiest thing for me is to think of where they fall in the food web. Anchovies (cooked of course), sardines, shrimp, and shellfish are pretty low in the chain so they're
I know that fish that are predators of other predators (like tuna and salmon) have been deemed safe for occasional consumption. I think it was once a month, but that could be me being extra cautious.... Salmon and Tuna are high up in the ocean's food chain so they are ingesting the mercury of the fish they eat, plus the fish that those fish ate, etc., etc. until you get back down to the plankton eaters, who filtered smaller amounts.
That said I have had both tuna and salmon during my pregnancy. Though only a few times each spread over the 24 weeks, thus far. Besides I think there are some great benefits (omega-3's) to eating salmon. (I've also eaten shrimp, crab, and fried oysters- puh-leez what isn't good fried?!)
I know..... TMI but I couldn't help it. Its the marine scientist in me
Oh. For the salmon (or any fish really) make sure it is wild caught. The farmed stuff typically has a bunch of antibiotics in it, which IMO is worse that a little bit of mercury here and there. And they artificially color it to give it the pretty "salmon" color of the wild caught- ewww.
The Monterey Bay Aquarium has a list of which fish are best to eat (both environmentally and they also indicate those high in mercury). You can check it out here: