EUGENE, Ore. – ODFW staff responded to a report made to the Oregon Invasive Species Hotline on Wednesday, Dec. 18, that a koi (fish) was spotted near the Armitage Boat Landing on the McKenzie River near Eugene.

District fish biologists removed the large koi which was most likely intentionally released into the McKenzie River. Koi can live up to 25 years, reproduce rapidly, and can survive very cold winters. Mature koi can produce 5,000 to 10,000 eggs and the largest koi can lay 500,000 eggs.

“Introduced, non-native fish can spread deadly diseases to wild fish populations,” said Jeff Ziller, ODFW District Fish Biologist. “There are plenty of examples in other states and countries where koi have damaged or changed aquatic ecosystems so extensively that vast amounts of public resources have been allocated to eradicate them, largely unsuccessfully,” added Ziller.

Koi are omnivores with a voracious appetite, consuming fish and amphibian eggs, aquatic insects, and competing with native fish for food. They also stir up sediments while uprooting and consuming aquatic plants which can reduce forage and cover for waterfowl and other animals.

Once non-native species are introduced to a waterbody, they are nearly impossible to remove. Help spread the word to never dump unwanted fish or aquarium contents in or near waterways, streams, ponds, lakes, or stormwater drains. It can have serious ecological consequences and can ruin recreational opportunities for future generations of Oregonians. 

ODFW staff appreciate the report to the Invasive Species Hotline. Non-native, invasive species, such as koi, can be reported to the hotline at 1-866-INVADER.