A federal study of mercury contamination conducted by the US Geological Survey was released last week, finding the toxic substance in every fish tested in nearly 300 streams across the country. This is the most comprehensive look to date at mercury in the nation’s streams. With mercury levels becoming widespread, it is increasingly more difficult to decipher which fish are the safest to consume in order to avoid harmful effects such as damage to the nervous system and impaired mental functioning. ChicagoHealers.com practitioner Dr. Steven Arculeo breaks down the most common fish to avoid along with the safest to consume, in order to avoid mercury poisoning: Fish with lower levels of mercury include anchovies, sardines, salmon, shrimp, light canned tuna and crab. Those with high levels are shark, swordfish, king mackerel, albacore canned tuna and tilefish. The EPA suggests eating no more than 12 ounces, or two average meals, of fish lower in mercury and no more than 6 ounces, or one average meal, of fish higher in mercury each week for healthy adults. Considering how important it is to get omega-3 fatty acids, found in fattier fish like sardines and salmon but also mackerel, these guidelines will help you make better choices.