Maryland wants people to eat more blue catfish to keep the invasive species from gobbling up the Chesapeake Bay’s prized blue crabs and striped bass.

But there’s one catch: Blue catfish are predators and can pick up toxic contaminants from their prey. So, a regular diet of tainted fish could increase a person’s long-term health risks.

Biologist Joe Love (left) and Eastern regional freshwater fisheries manager Brett Coakley, both with the Maryland Department of Natural Resources, handle a large blue catfish caught by electro fishing in Marshyhope Creek on the Eastern Shore. Credit: Dave Harp

The Maryland Department of the Environment recommends that people avoid eating any blue catfish caught recreationally in the Anacostia River near the District of Columbia. They have been found to harbor unsafe levels of polychlorinated biphenyls, or PCBs, a group of once widely used chemicals that has been banned since 1979 because of their toxicity.

For the same reason, MDE recommends limiting meals of blue catfish caught in the Potomac River from the District of Columbia line all the way downriver to the Bay, and from the Middle River near Baltimore. Since bigger blue catfish tend to pick up more contaminants, MDE suggests not eating any lunkers longer than 30 inches from the Potomac.

Because children 6 years old and younger are more vulnerable than adults to contaminants, MDE also urges limiting their meals of blue catfish from those rivers, as well as from the Choptank, Nanticoke, Patuxent and Wicomico.

There are similar consumption advisories for recreationally caught blue catfish in some Virginia rivers, and the District of Columbia urges limiting consumption of any fish, not just blue catfish, caught in its portions of the Anacostia and Potomac.

While meant to protect public health, such varied warnings can seem confusing, and they complicate Maryland’s decade-long efforts to promote the harvest and consumption of invasive fish.

Native to the Mississippi River, blue catfish were introduced in a few Virginia rivers in the 1970s but have since spread throughout the Bay watershed. In some rivers, they have become the dominant fish, raising concerns about their impact on crabs and other commercially valuable native fish.

In March, Maryland Gov. Wes Moore asked for federal assistance to cope with what he characterized as a fisheries disaster in the state tied to the proliferation of blue catfish and other invasive fish.

To support the state’s campaign to boost public appetites for blue catfish, MDE is undertaking another round of testing this year for contaminants in the fish to update and broaden its advice.

With help from the Maryland Department of Natural Resources, MDE plans to analyze 20 fresh blue catfish samples from tidal and nontidal waters of the Chester, Nanticoke, Patuxent and Susquehanna rivers, according to spokesman Jay Apperson.

MDE is also taking a fresh look at contaminants in two other invasive species, flathead catfish and Northern snakeheads.

In big blue catfish collected earlier this year by DNR, the department is looking for PCBs and mercury, the two contaminants responsible for most fish consumption advisories throughout the Bay watershed. The results of that analysis will be used to update advisories and possibly provide new ones for additional waterways, Apperson said.

Because PCBs tend to accumulate in fatty tissue, MDE recommends removing the dark meat while filleting blue catfish prior to cooking. Studies indicate that can reduce the contaminants consumed by up to 80%, the agency said.

MDE also has analyzed some blue catfish caught earlier for the contaminants known as PFAS, or per– and polyfluoroalkyl substances, sometimes called “forever chemicals.”

The agency issued a consumption advisory in 2021 for a few species of freshwater fish from Piscataway Creek in Prince George’s County where PFAS contamination had been detected. But Apperson said MDE officials have made no decision at this time to issue new or amended advisories for blue catfish as a result of PFAS.

This article was originally published on and is republished with permission.

Tim Wheeler is the Bay Journal's associate editor and senior writer, based in Maryland. You can reach him at 410-409-3469 or

Leave a comment

Leave a Reply