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Invasive Species

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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.

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.

U.S. Geological Survey


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 410-260-8325 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.


Crayfishes are popular bait in Maryland. However, some of the crayfishes used for bait are non-native and don’t belong here. If released alive, they can eliminate native species and cause irreparable damage to aquatic ecosystems, affecting everything from algae to sport fishes. Five non-native species are now established in Maryland waters. To prevent the spread of non-native, invasive crayfishes, anglers should: 1) never transport crayfish collected in one place to another; 2) never release live crayfish; and 3) inform other anglers of the threat of these invasive species to their favorite fishing spots.

DNR reminds anglers that it is illegal to dump unused crayfish or live bait of any kind into Maryland waters. The use and possession of all crayfishes are prohibited in the Upper Potomac, Middle Potomac, and Lower Susquehanna River basins unless the head is immediately removed behind the eyes upon capture. The possession and transfer of several non-native crayfishes are prohibited. To learn more, visit Refer to the online version of this guide for updated crayfish regulations—

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.

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

The 2014/2015 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 be held at the Maryland Fishing Challenge Finale event in September 2015. To learn how to enter and see contest rules, go to

Regulations in red are new this year.

Purple text indicates an important note.

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