Grass carp can be a good option to control aquatic vegetation

Published on Saturday, 24 May 2014 23:09 - Written by Chad Gulley Extension Agent

Landowners with farm ponds look at various options to control weeds in the pond. Grass carp may offer biological control of some unwanted aquatic vegetation. Grass carp may be a good option for some, but stocking grass carp requires a permit application process.

Vegetation in a pond can be important in maintaining good fish communities. Vegetation also can provide food for other wildlife species. If we have too much growth of certain aquatic plants, control may be warranted to remove some of the vegetation.

The grass carp is a vegetarian fish native to the Amur River in Asia. Grass carp feed on plants and do not prey on fish eggs or other fish species. The U.S Fish and Wildlife Service introduced grass carp into the United States in 1963 for experimental purposes. Since 1992, Texas has allowed stocking of the triploid grass carp, which is a sterile form of the species, to control nuisance vegetation.

In Texas, only triploid grass carp are legal and a permit from the Texas Parks and Wildlife Department is required before they can be purchased from certified dealers. A list of certified dealers is available within the instruction packet on the Texas Parks and Wildlife Department’s Triploid Grass Carp Information page at .

Grass carp are an effective biological control option for unwanted aquatic vegetation in a farm pond. Grass carp will seldom control aquatic vegetation the first year they are stocked. They control a wide variety of aquatic vegetation but they do have preferences. Grass carp will not control all aquatic vegetation species.

Plants like bushy pondweed, American pondweed, and hydrilla, for example, are a few of the preferred food species of grass carp.

Stocking rates for grass carp range in the seven to 15 fish per surface acre or higher. Grass carp travel in flowing water and will swim out in the event of an overflow. The Texas Parks and Wildlife may require the landowner to build an emigration barrier to prevent these carp from leaving the farm pond and entering major water bodies in the event of an overflow. Information and diagrams on emigration barriers around the spillways of farm ponds also can be found in the above mentioned information on the TPWD’s website. Grass carp should be 10 inches to 12 inches long when stocked to prevent being eaten by bass or other fish species.

Some ask, “If the grass carp are sterile, why is a permit required? Why be concerned with escapement into public waters?” The Texas Parks and Wildlife Department permit these fish so they can keep track of the location and the number of grass carp in the environment, especially near sensitive areas. The concern is due to escapement into major water bodies. They can live for many years and potentially could migrate to sensitive areas and consume a great deal of vegetation. Texas major water bodies are heavily dependent on natural aquatic vegetation.

Grass carp can live for at least 10 years and maybe longer in Texas waters. Grass carp grow rapidly and may exceed 60 pounds. Grass carp feed from the top of the plant downward. Grass carp appear to go dormant during the winter and resume feeding when water temperatures reach 68 degrees. Grass carp because they eat plants are difficult to catch with conventional fishing methods.

Educational programs of the Texas A&M AgriLife Extension Service are open to all people without regard to race, color, religion, sex, national origin, age, disability, genetic information or veteran status.