Pond Renovation

Introduction   |    What is Rotenone?   |   Preparing the Pond   |   Applying Rotenone   |   Restocking the Pond   |   Toxicity and Neutralization   |   Partial Fish Kill   |  

Click here for a printable version of this publication: Using Rotenone To Renovate Fish Populations In Farm Ponds

What is Rotenone?

Rotenone is a naturally occurring substance found in the roots and stems of several tropical plants. Jewel vine (Derris spp.), Lacepod (Lonchocarpus spp.), and hoary pea (Tephrosia spp.) are the more common plants from which rotenone is derived. Rotenone has many common and brand names, including Cube, Derris, Fish-Tox, Nox-Fish, Prentox, Nusyn Nox-Fish, rotenone dust, and Chem-Fish. It has other uses, including use as a garden dust to control insects and as an insecticide for use on cattle, dogs, and sheep.

Rotenone works by inhibiting a biochemical process in the fish cells, resulting in an inability of fish to use oxygen in the release of energy during normal body processes. In effect, the fish suffocate due to lack of oxygen. But, contrary to popular belief, rotenone does not remove oxygen from the water. Fish treated with rotenone move to the shallow water or to the surface of deeper water, gasping for oxygen within a few minutes of exposure to the chemical. Response of fish species to rotenone varies, and it is a good idea to know what species are in the pond before treatment .

Rotenone is an unstable compound that breaks down when exposed to the environment. It is ultimately converted to carbon dioxide and water. The breakdown process is rapid and is affected by temperature, light, oxygen, and alkalinity. At 80 degrees Fahrenheit, treated water will detoxify in about 4 days. In cooler water, the breakdown process is slower; at 45 °F, it can take 30 to 35 days for rotenone to detoxify. Most waters are safe for restocking within 5 to 6 weeks. In general, the cooler the water, the longer rotenone persists.

Rotenone is available at most farm and chemical supply stores. It is classified as a "restricted use pesticide" and cannot be purchased without a private pesticide applicator's certificate. These certificates can be obtained by contacting your county Extension agent