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Fish and Game kills thousands of invasive goldfish in Idaho pond

Biologists believe that someone deliberately dumped the fish in Heagle Pond in Hailey.
Credit: IDFG
Idaho Fish and Game staff remove thousands of dead fish from Heagle Pond in Hailey.

HAILEY, Idaho — Most people would not think of goldfish as an invasive species, but biologists warn that they can threaten native fish populations in Idaho.

Earlier this spring, Idaho Fish and Game received reports of illegal dumping of goldfish in Heagle Pond in Hailey. Fisheries biologists returned to the pond this week to treat the water with rotenone, a natural plant-based substance that is toxic to fish. The rotenone will degrade naturally in the pond over the next few weeks.

In addition to thousands of goldfish, fathead minnows, koi and perch were killed by the rotenone treatment and collected from the pond. 

"The illegal introduction of invasive species into Idaho's waters is an extremely concerning situation," said Mike Peterson, Regional Fisheries Manager. "What we found today is that the goldfish that were illegally introduced into Heagle Pond were successfully spawning, which could put the fisheries in the Big Wood River at risk."

Goldfish are a member of the carp family, which have never been documented in the Wood River Basin.

A perch was also found in the pond which is a fish species that does not belong in Wood River Valley ponds. According to biologists, finding a perch is a perfect example of a deliberate action by someone who illegally transported a live fish and put it into Heagle Pond.

"Illegal introductions and the necessary actions to remove the invasive species take money away from regional fisheries projects," said Joe Thiessen, Regional Fisheries biologist. "We had to divert limited license dollars to deal with a situation that was caused by someone dumping their pet goldfish into Heagle Pond."

In Idaho, a person illegally transplanting or introducing fish where they don't belong can be held legally responsible for the financial costs to restore the fishery to its prior condition. And it can potentially result in a felony charge.

Heagle Pond is currently is fenced off and signs are posted to keep people and pets safe. Idaho Fish and Game is continuing to monitor the pond and any additional dead fish will be collected and disposed of at a certified disposal facility. 

Credit: IDFG
Fish and Game killed off thousands of invasive fish in Heagle Pond in Hailey.