What polluted water means for your catch and your health

Polluted water can hold fish worth eating, but the pollution concentrates in their flesh, organs, and fat. The contaminants that matter most are mercury, PCBs (polychlorinated biphenyls), and bacteria — they build up over time in the fish's body and stay there even after cooking. You cannot see, smell, or taste them. The risk is real but manageable: you reduce it by knowing which fish to keep, how much to eat, and how to prepare them.

Different waterways carry different hazards. A river downstream from an industrial site may have high mercury. A lake near old landfills may have PCBs. A creek running through urban stormwater may carry bacteria and heavy metals. The pollution level also shifts with rainfall, season, and what industries or activities are upstream. This means the same water can be safer at one time than another, and the same species of fish can be safer in one part of a river than another.

Your state's fish consumption advisories tell you which waters have known problems and which fish from those waters are safest to eat. These advisories are based on actual testing, not guesses. They are your most reliable tool before you fish.

Key Takeaways

  • Check your state's fish consumption advisory for the specific water you plan to fish — it names which species are safe to eat and how often.
  • Smaller, younger fish of the same species usually carry less mercury and PCBs than larger, older ones, so keep the smaller catch.
  • Removing the skin, fat, and organs before cooking removes a significant portion of accumulated contaminants.
  • Eating a variety of fish species from different waters spreads your exposure across different contaminants rather than concentrating it in one type.
  • Pregnant people, nursing people, and young children should follow stricter limits than the general advisory, because their bodies are more sensitive to mercury and PCBs.

Finding your state's fish consumption advisory

Every state with inland waters publishes a fish consumption advisory, usually through the state health department or environmental protection agency. The advisory lists specific waters (named lakes, rivers, or sections of rivers), the fish species found there, and how often a person can safely eat them. Some advisories say "one meal per week," others say "one meal per month," and some say "do not eat" for certain species in certain waters.

To find yours, search "[your state] fish consumption advisory" or go to your state health department's website and look for "fish advisories" or "water quality." The EPA also maintains a searchable database at epa.gov/waterdata/fish-consumption-advisories, though the state version is usually more current and detailed. Write down the advisory for your water before you fish — do not rely on memory or what other anglers tell you.

If your water is not listed, that does not mean it is clean. It means either the state has not tested it or the testing found no problem. Call your state environmental agency if you are unsure whether a water has been tested. Some smaller streams and ponds are not monitored regularly.

Which fish to keep and which to release

Size matters more than species. A large bass from a polluted lake holds more mercury than a small bass from the same lake, because the fish accumulates contaminants over its lifetime. If your advisory says "eat no more than one meal per week of largemouth bass," that limit applies to a 15-inch fish, not a 20-inch fish. Keeping smaller fish also helps the population recover.

Bottom-feeding fish and predatory fish accumulate more contaminants than mid-water feeders. Catfish, carp, and bullheads spend time on the bottom where sediment collects pollutants. Pike and bass, which hunt other fish, concentrate whatever those prey fish contained. Panfish like bluegill and crappie, which eat insects and small organisms, usually carry less. If your advisory does not specify, assume bottom feeders and large predators are riskier than smaller panfish.

Some waters have different advisories for different species in the same location. A lake might say "eat walleye once per week" but "eat pike no more than once per month." This reflects actual testing of those fish in that water. Follow the specific advisory for the species you caught, not a general rule.

Cleaning and preparing fish to reduce contaminants

Contaminants concentrate in the skin, fat, and organs. Removing them removes a significant portion of what you are trying to avoid. Fillet the fish and discard the skin — do not just scale it. Cut away the dark meat along the lateral line (the stripe running down the side), which holds more fat and contaminants than the white meat. Remove the organs completely, including the liver and any roe.

Trim the belly fat and any other visible fat deposits. Fat-soluble contaminants like PCBs live in fat tissue. A fish that looks lean after trimming is safer than one prepared whole or with skin on. Baking, broiling, or grilling on a rack allows fat to drip away; frying in oil or making a stew keeps the fat in the dish.

Cooking does not destroy mercury or PCBs — heat does not break them down. Cooking only kills bacteria. If your concern is mercury or PCBs, preparation and trimming matter far more than cooking method. If bacteria is the concern (which is more common in urban stormwater-affected waters), cook the fish thoroughly to an internal temperature of 145°F.

How much and how often to eat fish from polluted water

The advisory gives you a frequency: "one meal per week," "one meal per month," or "do not eat." A meal is typically a 6-ounce serving for an adult — about the size of a deck of cards. If the advisory says one meal per week, you can eat one 6-ounce serving per week and stay within the safety margin. If it says one meal per month, eating more than that increases your exposure.

These limits assume you are eating only fish from that one water. If you fish multiple polluted waters, you need to account for all of them. Eating one meal per week from Lake A and one meal per week from Lake B means you are eating two meals per week total, which may exceed the safe level if both waters have the same contaminant. Vary your sources and keep a rough log of what you caught and where.

Pregnant people, nursing people, and children under 8 should follow stricter limits — usually one meal per month or less for species with higher mercury. Mercury damages developing brains. Check whether your state advisory has a separate section for vulnerable groups; if not, assume they should eat half as much as the general population.

Testing your water if no advisory exists

If your state has not tested a water you fish regularly, you have a few options. Some universities and cooperative extension offices offer low-cost fish tissue testing — they will analyze a sample of your catch for mercury and PCBs. Contact your state university's environmental science or fisheries department to ask whether they offer this service. Results take several weeks.

You can also contact your state environmental agency and ask whether they plan to test that water. If enough people ask, they may prioritize it. In the meantime, apply the precautionary approach: treat it as if it might be polluted, keep smaller fish, trim fat and organs, and eat less frequently than you would from a tested clean water.

Do not assume a water is clean because it looks clean. Pollution is often invisible. A river that runs clear can carry high mercury from upstream mining or industrial discharge. A lake that smells fine can have PCBs from old electrical equipment dumped decades ago.

Fishing in urban and industrial areas

Waters near cities, factories, highways, and old industrial sites carry higher risk. Urban stormwater runoff brings oil, heavy metals, and bacteria. Industrial discharge, even when regulated, can leave residues. Old landfills and Superfund sites near water are red flags. If you fish downstream from any of these, check the advisory first and assume the water needs caution.

Older industrial cities often have fish consumption advisories on nearly every waterway. This does not mean you cannot fish there — it means you need to follow the advisory carefully. Many people fish these waters their whole lives and eat from them regularly by respecting the limits. The risk comes from ignoring the advisory or eating far more than recommended.

Newer pollution sources, like microplastics and "forever chemicals" (PFOA and PFOS), are not yet fully covered by all state advisories because testing is still developing. If you fish in water near airports, military bases, or sites with aqueous film-forming foams (AFFF), ask your state environmental agency whether those contaminants have been tested in that water.

Frequently Asked Questions

Can I eat fish from a water with no advisory if it looks clean?

Appearance does not indicate safety. A clear, clean-looking river can carry high mercury or PCBs from upstream sources. If your state has not tested the water, assume it may be polluted and apply the precautionary approach: keep smaller fish, trim fat and organs, and eat less frequently than you would from a tested clean water. Contact your state environmental agency to ask whether testing is planned.

Does boiling or frying fish remove mercury or PCBs?

No. Heat does not break down mercury or PCBs. Cooking kills bacteria but leaves contaminants intact. Trimming skin, fat, and organs removes far more contamination than any cooking method. If you are concerned about mercury or PCBs, focus on preparation, not cooking.

Is it safe to eat fish from polluted water if I am pregnant?

Mercury during pregnancy can harm fetal brain development. If you are pregnant or nursing, follow your state's advisory for vulnerable groups, which usually recommends eating less frequently and choosing species with lower mercury. If no separate advisory exists, eat half as much as the general population recommendation. Discuss your local fish with your doctor if you fish regularly.

What if the advisory says "do not eat" for a species I caught?

Release it. "Do not eat" means the contaminant level is high enough to pose a real health risk, especially with repeated exposure. It is not a suggestion — it is based on testing. Catch-and-release is the right choice for species under a "do not eat" advisory.

Can I reduce risk by eating only the white meat and avoiding dark meat?

Yes, partly. Dark meat holds more fat and contaminants than white meat. Removing skin, organs, and belly fat removes even more. Together, these steps can reduce your exposure by 50 percent or more. But they do not eliminate the risk entirely — the advisory limits still apply to the cleaned fish.