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Invasive Species

The introduction of invasive and non-native species can cause irreversible changes in the food web. Several invasive species of concern are listed below. For information on other invasive and non-native species, and to see a list of species prohibited from transport, visit To report the illegal transport or unauthorized introduction of invasive species, contact the Natural Resources Police—800-635-8124.

Zebra Mussels

Zebra mussels are an aggressive invasive species and reproduce at a very prolific rate, out-competing native species for needed resources. These mussels quickly overtake and cover all available areas to such an extent that they can clog water intake structures, boats, moorings, ropes, fishing lines, traps, and even dams and power plants. Zebra mussels are established from the Susquehanna River and Flats to the upper Bay. Additionally, DNR recently confirmed the presence of zebra mussels in tributaries of the upper Western Shore near Middle River in Baltimore County.

More information on zebra mussels is available at, including a fact sheet and reporting form. DNR asks citizens, to report any suspected sightings to



Please Catch and Keep Northern Snakeheads

It is against Maryland, Virginia, and federal laws to possess, import, or transport live northern snakehead.

If you catch a snakehead and want to keep it, you must immediately kill the fish by removing its head, gutting it or removing its gill arches. The capture and possession of dead snakeheads is not subject to any season, creel limit or size limit.

DNR asks anglers to report snakeheads caught outside of the Potomac River and its tributaries or upstream of Great Falls. Send catch information to or call 410-260-8300 to help DNR track the range of the species.

If you catch a northern snakehead with a blue or red tag, please report the tag number and the location, date and time of day when the fish was caught to the U.S. Fish & Wildlife Service at 800-448-8322.

Blue & Flathead Catfish

Blue and flathead catfish are invasive species that have spread rapidly throughout the Chesapeake Bay and its tributaries. These catfish have few natural predators, eat a wide variety of native fish and shellfish, and may cause ecological harm.

It is illegal to move live blue or flathead catfish from one body of water to another and is punishable by a fine of up to $2,500. Anglers are encouraged to catch and keep blue and flathead catfish. There is no minimum size or creel limit for these catfish.

Harvest an invasive fish and help DNR to monitor the spread of invasive species

The Maryland Fishing Challenge includes an Invasive Species Component. Anglers who report their catch and harvest of a blue catfish, northern snakehead or flathead catfish will be entered into a special invasive species drawing. To learn how to enter and see contest rules, go to

fish importation

It is illegal to introduce any fish species into Maryland waters except bait fish on a hook for angling.

This prevents the introduction of disease and the spread of species that could compete with native species.

Do not release aquarium fish to the wild, and never transfer fish from one area to another.

To import or stock fish in Maryland, suppliers must register with the Department and comply with Maryland fish health requirements to ensure that stocked fish do not impact resident fish.

A permit is required to stock fish into any Maryland waters, including private ponds. Contact or call 410-260-8300 for more information on registering and obtaining a permit.

Regulations in red are new this year.

Purple text indicates an important note.

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