Using Grass Carp to Control Aquatic Plants

If you are having issues with aquatic plant control in your pond, you might consider introducing grass carp to your pond. These fish, originally from Asia, have been imported to the United States since the 1960s to be intentionally released into our waterways for aquatic plant control. In 1994, Pennsylvania made it legal to import grass carp as long as they are the triploid variety. This means they have been bred to have an extra set of chromosomes and are, therefore, sterile. Triploid grass carp are not able to reproduce and spread out of control.  However, care should be taken to ensure that they do not escape into nearby water bodies to prevent unintended impacts on aquatic communities.  

Grass carp rely almost entirely on aquatic plants for their diet. According to the PA Fish and Boat Commission, they prefer to eat the following aquatic plants:

• Pondweeds (Potamogeton species)
• Common elodea
• Coontail
• Naiad
• Duckweed
• Watermeal
• Chara/Muskgrass
• Watermilfoil
• Bladderwort
• Water-stargrass

They usually do not eat or control filamentous algae, large-leaf pondweed, cattail, bulrush, arrowhead, burreed. watershield, white waterlily and spatterdock.

Pond owners who wish to stock triploid grass carp in ponds of 5 acres or less must complete and submit a Triploid Grass Carp Pond Owner Stocking Permit Application and pay a permit fee to the PA Fish and Boat Commission. Ponds greater than 5 acres and, in instances where there is an increased potential of adverse environmental impacts, require additional reports, details of which can be found on the permit application.

Grass carp can only be purchased from approved triploid grass carp dealers, which are listed on the Pa Fish and Boat Commission website.