Fish is safe to eat for the vast majority of people, and eating it regularly is one of the better things you can do for your health. Two servings per week lowers your risk of heart disease, and the omega-3 fatty acids in fish help reduce blood pressure and triglyceride levels. The real question isn’t whether fish is safe, but which fish to choose and how to handle it properly.
Why Fish Is Worth Eating
The nutrients in fish, particularly omega-3 fatty acids, deliver measurable cardiovascular benefits. Eating at least two servings a week lowers the risk of heart disease and, specifically, sudden cardiac death. Omega-3s slightly lower blood pressure and reduce blood levels of triglycerides, a type of fat linked to artery damage. Fatty fish like salmon, sardines, mackerel, and trout are the richest sources.
Fish is also a lean, high-quality protein with relatively few calories. For pregnant and breastfeeding women, the omega-3s in fish support fetal and infant brain development, which is why guidelines actively encourage fish consumption during pregnancy rather than discouraging it.
Mercury: The Main Concern
Mercury is the contaminant most people worry about, and it’s a legitimate concern for certain species. Mercury accumulates in fish that are large, long-lived, and high on the food chain. The fish to avoid entirely are shark, swordfish, king mackerel, tilefish from the Gulf of Mexico, bigeye tuna, marlin, and orange roughy. These consistently carry the highest mercury levels.
Most common grocery store fish fall into the FDA’s “Best Choices” category, meaning they’re low enough in mercury to eat two to three servings per week without concern. This includes salmon, shrimp, pollock, tilapia, cod, catfish, canned light tuna, and sardines. Albacore (white) tuna is a step up in mercury and falls into the “Good Choices” tier, where one serving per week is the recommendation.
One nuance worth knowing: selenium, a mineral naturally present in most fish, may offer some protection against mercury’s toxic effects. Research from the U.S. Geological Survey found that common fish species have selenium-to-mercury ratios well above 1:1, with Chinook salmon averaging a ratio of 27:1. The science on how much protection this actually provides is still developing, but it helps explain why the health benefits of eating fish consistently outweigh the mercury risk for most species.
Pregnancy and Children
Pregnant and breastfeeding women should eat 8 to 12 ounces of low-mercury fish per week, split across two to three servings of about 4 ounces each. Sticking to the “Best Choices” list (salmon, shrimp, tilapia, cod, and similar species) keeps mercury exposure well within safe limits while providing omega-3s that benefit the baby’s developing brain.
Children need smaller portions scaled to their age: about 1 ounce per serving for ages 1 to 3, 2 ounces for ages 4 to 7, 3 ounces for ages 8 to 10, and 4 ounces at age 11. Two servings per week from low-mercury species is the target. The key mistake parents make isn’t feeding their kids too much fish. It’s avoiding fish altogether out of mercury fears, which means missing out on important nutrients during critical years of development.
Farmed vs. Wild Fish
The assumption that farmed fish is more contaminated than wild-caught doesn’t hold up. A study comparing farmed and wild Atlantic salmon found that wild salmon actually had higher levels of persistent organic pollutants (dioxins, PCBs, and organochlorine pesticides) as well as higher mercury. The reason: farmed salmon are increasingly fed plant-based diets, which reduces their exposure to ocean-borne contaminants. Both farmed and wild salmon tested well below European Union maximum limits for these pollutants.
Wild salmon did contain more DHA, one of the two key omega-3 fatty acids, while EPA levels were similar in both. So wild salmon has a slight nutritional edge, but farmed salmon is perfectly safe and still a rich source of omega-3s. Buy whichever fits your budget.
Microplastics and Other Contaminants
Microplastics show up in seafood, along with salt, honey, bottled water, beer, and many other foods. The FDA’s current position is that the levels of microplastics detected in foods do not pose a known risk to human health. Part of the challenge is that there aren’t even standardized methods yet for measuring microplastics accurately, so many studies use methods with limited reliability. This is an area being actively studied, but there’s no evidence right now that microplastics in fish should change your eating habits.
Raw Fish and Sushi
Eating raw fish carries a real risk of parasitic infection that cooked fish does not. Reputable sushi restaurants and fish labeled “sushi-grade” mitigate this through freezing, which kills parasites. The FDA’s requirement is freezing at -4°F (-20°C) for 7 days, or flash-freezing at -31°F (-35°C) until solid and then holding at that temperature for at least 15 hours. Home freezers typically don’t reach these temperatures reliably, so making sushi at home with fresh, unfrozen fish is riskier than eating it at a restaurant that follows proper protocols.
Pregnant women, young children, older adults, and anyone with a weakened immune system faces higher risk from raw fish and should stick to cooked preparations.
Safe Handling and Cooking
Fish spoils faster than most proteins, so proper storage matters. Raw fish keeps in the refrigerator for 1 to 3 days. In the freezer, fatty fish like salmon, tuna, and mackerel stays good for 2 to 3 months before quality degrades. If fish smells strongly of ammonia or has a slimy texture, discard it.
Cook fish to an internal temperature of 145°F (62.8°C). At this point, the flesh should be opaque and flake easily with a fork. One specific hazard to know about: certain fish, especially tuna, mackerel, and mahi-mahi, can develop histamine if left at warm temperatures too long. Histamine isn’t destroyed by cooking, so the safety window is really about keeping fish cold from the moment it’s caught. If a piece of tuna tastes peppery or metallic, stop eating it.
The Bottom Line on How Much to Eat
For most adults, two to three servings of fish per week is the sweet spot, balancing maximum nutritional benefit with minimal contaminant exposure. That works out to roughly 8 to 12 ounces total. Vary the species you eat rather than relying on one type, and lean toward the low-mercury options for your staples. If you eat high-mercury fish like ahi tuna occasionally, that’s fine. Problems arise from frequent, repeated exposure to the same high-mercury species over months and years, not from a single serving.