FWP removing goldfish from a private pond near Zortman

From Montana Fish, Wildlife and Parks

Montana Fish, Wildlife and Parks will be using the chemical rotenone to remove invasive goldfish from an unnamed private pond on upper CK Creek, approximately one mile from Zortman. Rotenone was to be applied to the pond Tuesday, and the chemical will remain in the water and slowly degrade for four-five weeks.

Signs will be placed around the pond and at nearby access locations, including the Square Butte Block Management Area. FWP encourages recreationists and their pets to stay away from the pond until the signs are removed. FWP will monitor the pond for several weeks until the Rotenone has completely degraded.

Goldfish are an aquatic invasive species that are capable of surviving in Montana waters. It's important for the public not to release goldfish into Montana waters, as removal efforts are expensive and use fishing license dollars that instead could be used to stock fish and improve fishing opportunities. 

"We attempted a non-chemical effort to remove the goldfish in 2016, when they were first confirmed, but it failed to remove all the fish," said fisheries biologist Cody Nagel "By removing all fish from this pond we will eliminate the risk of goldfish spreading to downstream locations, including Fort Peck Reservoir, where we definitely don't want them."

The environmental assessment and public comment process for this action was completed in July-August 2020.  However, treatment plans included waiting for the right conditions.

"Now is the ideal time to treat the pond as the cattle have been removed from this pasture and there is no inflow or outflow of water from the pond," Nagel added. "The treatment will only take a couple hours on the 0.13 surface-acre pond, but FWP will continue to monitor the pond for several weeks to ensure that all the goldfish have been removed." 

The chemical rotenone is a naturally occurring substance derived from the roots of tropical plants in the bean family.  It has been used by native people for centuries to capture fish and has been used in fisheries management in North America since the 1930s.

Rotenone is applied to the water and enters the fish through the gills, where it affects a fish's ability to breath. It is effective at very low concentrations because it is readily absorbed into the bloodstream through the thin cellular layer of the gills. Mammals, birds and other non-gill breathing organisms do not have this rapid absorption route into the bloodstream and are not affected by consuming treated water or dead fish at the concentrations used in fisheries management. 

Goldfish are the only species of fish in the pond. This pond has historically been fishless, and there are no plans to stock fish after goldfish are removed due to the pond's small size.

For more information or answers to questions, people can contact biologist Cody Nagel at 406-265-6177.