A new study finds that 84% of the world’s fish tested was not safe to eat more than once per month because of mercury poisoning. And 13% of the fish isn’t safe to eat in any circumstances. I'm not sure how one can eat something that is so poisonous that it's only safe enough to eat once every 30 days, quite frankly.
In Japan and Uruguay, the study found that “Mercury concentrations in fish from sites in Japan and Uruguay were so high that no consumption is recommended.” Yikes! And they were only measuring for mercury levels-- there's PCB contamination, pollutants, and sustainability practices to factor in as well.
Blue Ocean's website provides great information for what kinds of fish to eat and which to avoid. The best choices are Atlantic Mackerel, U.S.-farmed Tilapia, wild Alaska salmon, U.S. farmed shrimp, farmed clams/mussels/oysters, pacific sole and pole-caught mahi-mahi. Fish to avoid at all costs are imported shrimp, farmed salmon, shark, Atlantic cod, Atlantic halibut, Atlantic bluefin tuna, Chilean sea bass, orange roughy, grouper and Atlantic flounders and soles.