Invasive Fish

​We Need Your Help

Invasive Fish are not native to Maryland's ecosystem
and have been known to cause significant economic
or ecological harm, such as:

Loss of biodiversity, Altered aquatic food webs, Reduced water quality

Reduced public safety and health, Decline in fisheries and habitat

Damage to infrastructure, and ​Loss of tourism and recreation

Report Catching a Northern Snakehead, Blue Catfish or a Flathead Catfish
using Maryland's Invasive Species Tracker​

  • The department asks anglers to remove and kill any northern snakehead, blue catfish, and flathead catfish they catch.
  • Catch and release of these fish is discouraged, as they are invasive top predators and pose a serious long-term threat to our native species.
  • In Maryland, it is illegal to transport live snakehead, blue catfish, and flathead catfish into another body of water, anyone in violation of this can be fined up to $2,500.
  • To report illegal transport or unauthorized introductions of invasive species please contact the Natural Resources Police at 800-628-9944.

blue catfish

Blue Catfish: Invasive Species, MD DNR

Blue Catfish(Ictalurus furcatus)

Blue Catfish are long and often slender with a deeply forked tail. A distinguishing feature of the blue catfish is that the anal fin margin, or edge, is straight as if it has been clipped with scissors. All other catfish species have rounded anal fins.

Blue catfish are typically a bluish, gray color on top with a silvery or white underside. They are the largest of the catfish family in North America and can attain weights in excess of 100 pounds. The Maryland state record blue catfish is 84 pounds.

As an introduced species, blue catfish are now commonly found in the tidal Potomac River and some of the other tributaries of the Chesapeake Bay. Studies are currently underway to determine their impact on other aquatic species.

More information about the blue catfish can be found on the Blue Catfish Page.



Northern Snakehead: Invasive Species, MD DNR

​​Northern Snakehead (Channa argus)

Snakehead can be identified by their protruding lower jaw and sharp teeth. Their long single dorsal fin and long anal fins are composed of soft rays. Their skin markings contain dark irregular blotches along both sides. The also have a truncate (not rounded) tail.  In most regions, northern snakeheads grow up to 3 feet in total length​.​

As of October 4, 2002 it became a federal violation of the Lacey Act to import live snakehead fishes or viable eggs without a permit (Federal Register, 2002).​ 

Northern snakeheads are able to breath air. Breathing air aids its ability to live out of water for prolonged periods of time. The northern snakehead can survive out of water in harsh conditions such as mud or in water with little oxygen as long as it remains moist.

More information about the Northern snakehead catfish can be found on the Snakehead Page.​


​​flathead catfish

Flathead Catfish ​(Pylodictis olivaris)

Flathead differ greatly in appearance from most other catfish species. Flatheads have a squarish tail, sometimes slightly notched. Their backs and sides are often an olive or light brown color with darker mottles or specks. Their bellies are often white or pale in color. Their heads are compressed, or flattened, and they have a protruding lower jaw. Flathead catfish can reach sizes in excess of 100 pounds but much smaller specimens have been encountered in the Chesapeake Bay region.

Flathead are an introduced species and are currently found in only a few places in the Chesapeake Bay; the Potomac River, Upper Bay, Elk and Sassafras Rivers.

More information about the flathead catfish can be found on the Flathead Catfish Page.

Flathead Catfish: Invasive Species, MD DNR