Triploid Grass Carp Information and Permiting

On This Page:

Introduction to Triploid Grass Carp

Triploid grass carp

Triploid grass carp is a sterile (non-reproducing) form of grass carp. This fish is primarily a plant-eater and is a relatively inexpensive and effective biological tool to control some, but not all, species of nuisance aquatic vegetation. The following information helps landowners determine if triploid grass carp are a good solution for their water body and the plant species present, guide them through the application process, and provide information on permit management. Identification of the type of aquatic vegetation and determination if triploid grass carp can be effective vegetation control for that type of vegetation is the first step for landowners.

A permit is required to possess or transport triploid grass carp by the Texas Administrative Code. Owners of the water body (stock tank, pond or lake), their agents, or controlling authorities must obtain a permit from Inland Fisheries Division of the Texas Parks and Wildlife Department before stocking triploid grass carp. Permits are needed for stocking triploid grass carp in both public and private waters.

A permit is required to stock triploid grass carp, so that TPWD can ensure that the number stocked will not negatively affect aquatic ecosystems especially near sensitive areas, and facilitate communication with landowners on efficacy and tips on preventing fish escapement. Even though the fish cannot reproduce, escapement can pose serious threats to nearby non-target habitats. Triploid grass carp have a long-life span and the ability to consume a great deal of vegetation, putting sensitive ecosystems at risk. Ensuring that triploid grass carp remain where they are stocked makes economic sense for the water body owner and helps protect beneficial aquatic vegetation in public waters.

In 1992, TPWD began allowing landowners to stock triploid grass carp using a permit. Triploid grass carp is a sterile (non-reproducing) form of the species that was introduced into the United States in 1963 for experimental purposes. Sterility of all triploid grass carp sold in Texas is validated by the US Fish and Wildlife Service.

The outstanding freshwater fisheries in Texas are often supported by moderate levels of aquatic vegetation. This vegetation provides benefits, including cover for young fish to hide from predators, food and cover for insects that are consumed by fish, and structure in which sportfish use for resting and feeding. However, some plants can grow to nuisance levels, degrade water quality, reduce feeding efficiency of sportfish, inhibit recreational access, and require treatment. 

Back to the top

Will Triploid Grass Carp Work for You?

Grass carp have definite food preferences. Before deciding to stock grass carp, it's important to identify the vegetation you want to control. Bushy pondweed, American pondweed, and hydrilla are preferred foods. Grass carp are not effective for bulrush, filamentous algae (pond scum or moss), water primrose, coontail, Eurasian milfoil, or cattails.

It may take several years to achieve control using triploid grass carp (see stocking guidelines).

AquaPlant – a Diagnostics Tool for Pond Plants and Algae, provided by Texas A&M AgriLife Extension, is an excellent source for plant identification and plant control information.

Back to the top

Application for Permit to Stock Triploid Grass Carp

Notice of Permitting Agreement
It is the responsibility of the applicant to read and understand the information provided on the Triploid Grass Carp regarding the regulations, pond management, preventing escapement, and permitting information.

Approval of application is not guaranteed. Applications will be reviewed by a department representative and stocking of triploid grass carp may not be authorized in environmentally sensitive areas where threatened, endangered, or unique species occur. Please allow up to four weeks for review of applications.

Click the link above to log in to Texas Parks and Wildlife Permitting or follow the directions below for 'Establishing a Permit Account'.

Back to the top

Establishing a Permit Account

Email addresses are required to utilize the permit system. If you do not have an email address, you may create a free email Gmail or Yahoo account, or contact a trusted friend or relative to assist you.

Existing permit holders, TWIMS, and LMA users, go to TPW Permitting and log in using your email address and password, or select Forgot Password. 

New permit applicants, go to TPW Permitting and click ‘Create Account ‘ to set up your new account.

If you receive an error message, email the permit coordinator your full name, telephone, TxDL and DOB for your account to be confirmed or combined.  Requests are generally completed within three to five business days.  Once completed, instructions will be sent via e-mail.

Back to the top

Contact Information

Contact the Triploid Grass Carp Permit Coordinator at (512) 389-4742 or via email.

Back to the top

Application Fees

Private Water Applicants
Applications for private water will be charged an application fee comprised of two parts:

Applicants have the option to pay with a debit or credit card or pay by check. Payments by check must include the remittance document created at the time of check out.

Triploid grass carp must be purchased from an aquaculture vendor.

Public Water Applicants
Fees are waived for public water applications. A public water body is defined as bays, estuaries, and water of the Gulf of Mexico within the jurisdiction of the state, and the rivers, streams, creeks, bayous, reservoirs, lakes, and portions of those waters where public access is available without discrimination.

Controlling authorities are advised to contact the permit coordinator or TPWD Inland Fisheries Management District prior to applying. Inland Fisheries Management Regions and Districts

Triploid grass carp must be purchased from an aquaculture vendor.

Back to the top

Purchasing Triploid Grass Carp

The link below includes a list of individuals/companies permitted to sell triploid Grass Carp in the state of Texas. Out of state companies delivering/selling triploid Grass Carp in Texas must be permit holders.

Holders of triploid Grass Carp permits for pond stocking may travel outside the state to purchase triploid Grass Carp from lawful sources in another state, provided the fish are accompanied on import into Texas by an aquatic product transport invoice and documentation that the grass carp have been certified as triploid by the Grass Carp Inspection and Certification Inspection Program operated by the U.S. Fish and Wildlife Service.

Permitted Vendors for Triploid Grass Carp

Permit Requirements and Recordkeeping

All persons in possession of triploid Grass Carp must possess and retain for a period of one year from the date the grass carp were obtained or as long as the grass carp are in the water an exotic species transport invoice (from a permitted seller) or an aquatic product transport invoice (if obtained out of state) and documentation that the grass carp have been certified as triploid by the Grass Carp Inspection and Certification Inspection Program operated by the U.S. Fish and Wildlife Service.

Permits are valid for the quantity of carp permitted for stocking of triploid grass carp into the waterbody specified on the permit. 

Permit is valid for 36 months from the date of issuance, or until all grass carp authorized by the permit have been purchased/stocked, whichever occurs first. Permittee may purchase fewer carp than total quantity permitted; remaining quantity may be purchased prior to the permit expiration date of 36 months from the date of issuance but cannot be purchased/stocked after the permit expires.

Back to the top

Stocking Guidelines

It may take several years to achieve control using triploid grass carp. Restocking, generally every 5 to 7 years, is needed for maximum effectiveness.

Recommended stocking rate for triploid grass carp is five per acre if the water body has 50% or less plant coverage, and up to 10 per acre if plant coverage is greater than 50%.

The permit system calculates the recommended quantity of carp based upon the inputs from the applicant.  Requesting greater quantities of carp than the recommended amount is not advised. If overstocked, all submersed aquatic plants may be eliminated. If insufficient numbers are stocked, less-favored plants may become overabundant.

Triploid grass carp should be 10-12 inches long when stocked. Smaller carp are likely to escape or be eaten by predator fish such as catfish or bass. Notify the aquaculture vendor if large catfish or bass are present in the water body.

Early spring is the ideal time to stock. To enhance effectiveness of triploid grass carp, overabundant vegetation can first be reduced by winter die-off, herbicide treatment, or water-level drawdown to promote grazing on re-growth.

Back to the top

About Triploid Grass Carp

The grass carp is a primarily plant-eating fish native to the Amur River in Asia and is a relatively inexpensive and effective biological tool to control some species of nuisance aquatic vegetation. Keep in mind, however, that the types of plants these fish prefer may also be important for sportfish habitat and waterfowl food and, in large numbers, grass carp may become invasive and cause harm to the ecosystem. Aquatic vegetation can be important in maintaining good fish communities and providing food for other wildlife species. Stocking grass carp may also result in alga blooms and reduced water clarity. Where all submersed vegetation has been eliminated, the water can become turbid (murky) as the hungry fish eat organic material out of the sediment.

Grass carp:

Back to the top

Preventing Escape

Triploid grass carp seek flowing water and often escape before controlling nuisance aquatic plants. Escapement reduces or eliminates potential for plant control within targeted areas and threatens beneficial plants outside of targeted areas. If they escape, they may have negative impacts on native ecosystems. Impoundments on permanently flowing creeks, or those that overflow frequently, should not be stocked with triploid grass carp unless they can be effectively screened. Emigration barriers are required for many, and recommended for most, water bodies being stocked with triploid grass carp. Ensuring that triploid grass carp remain where they are stocked makes economic sense for the water body owner and helps protect beneficial aquatic vegetation in our public waters. In cases where emigration cannot be prevented, chemical or mechanical control of aquatic plants is recommended.

Posts with steel bars
Figure 1 - Spillway Barrier

With few exceptions, the best screening device for nearly all outlet types is the horizontal parallel steel-bar design. The orientation of the bars allows unrestricted passage of small debris, thereby minimizing maintenance, clogging, and flooding concerns. Bar thickness of ¼- to ½- inch is preferred. Round bar stock will facilitate debris passage. For a spillway barrier (Figure 1), the horizontal bars are attached to vertical support posts (minimum ¾-inch diameter) spaced 4 feet apart. Horizontal bars should be spaced 2 inches apart. The barrier should span the entire spillway. Since triploid grass carp are excellent jumpers, barrier height should extend 2 feet above the normal high water level.

diagram of pipe with bars
Figure 2 - Drainage Pipe Cap

For capping a drainage pipe (Figure 2), a similar bar design should be used. Extending the bars 4-5 feet above the overflow pipe allows water to rise over debris and begin flowing again should the screen become clogged.

Welded wire and chicken wire are not effective as barrier materials. These types of materials readily clog with debris and the force of even a small amount of water can destroy the barrier. Clogged barriers may threaten the integrity of dams. 

Back to the top

Methods for Aquatic Plant Control

Control options fall into four basic categories: mechanical, environmental, biological, and chemical (herbicides). Each method has advantages and disadvantages. Factors to consider include effectiveness, cost, availability, ease of application, potential environmental consequences, and whether special permits are required. Additional information can be found in the Managing Nuisance Aquatic Plants (PDF).

Management of nuisance aquatic vegetation in public water is regulated under the State Aquatic Vegetation Plan. Under the plan, a treatment proposal must be filed with the Texas Parks and Wildlife Department and the controlling authority for the lake or stream in question. Treatment proposals are not required for private water, but treatment with a restricted or limited-use herbicide requires certification from the Texas Department of Agriculture.

Public Waters Stocked with Triploid Grass Carp

Grass carp are rarely caught by anglers, but it happens on occasion.  If a grass carp is caught in public waters where they have been stocked, it must be immediately returned to the water unharmed. A current list of these water bodies can be found at Public Waters Stocked with Triploid Grass Carp.

Back to the top