JAMESTOWN, N.D. -- Invasive zebra mussels recently were found in moss balls at pet stores in North Dakota and several other states but since have been removed from the shelves, the state Game and Fish Department said Monday.

The round, algae-like organisms are popular among aquarium owners.


Game and Fish was notified about the contaminated moss balls last week after a U.S. Fish and Wildlife Service inspection in Seattle found zebra mussels in a moss ball shipment from Ukraine, said Ben Holen, aquatic nuisance species coordinator for the Game and Fish Department in Jamestown.

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“It quickly became apparent that this was not an isolated incident but a national issue,” Holen said.

A Game and Fish Department check of pet stores across the state confirmed contaminated moss balls at pet stores in Fargo and Bismarck, Holen said, and the products were removed from the shelves.

“This was something that was new to all of us,” he said. “It was a very surprising and interesting week last week when we got that original call from the U.S. Fish and Wildlife Service.”

A zebra mussel is seen on a moss ball in this photo provided by the North Dakota Game and Fish Department.
A zebra mussel is seen on a moss ball in this photo provided by the North Dakota Game and Fish Department.

Game and Fish is encouraging anyone who recently purchased moss balls to properly dispose of them by placing in a bag, freezing solid and discarding them into the trash.

Moss balls shouldn’t be put down toilets or drains.

Holen called the incident “highly concerning” and yet another example of how easily zebra mussels and other aquatic invasive species can hitch a ride into a new body of water.

“States spend a ton of money to fight ANS and aquatic nuisance species,” Holen said. “This was very, very alarming and just goes to show that there are multiple pathways toward ANS introductions.”

Native to fresh waters in parts of Europe and Asia, zebra mussels are invasive mollusks that clog water intakes and interrupt aquatic ecosystems by outcompeting and attaching to native mollusks and filtering out algae that native species need for food, according to the U.S. Geological Survey.

In North Dakota, zebra mussels have become established in the Red River, the Sheyenne River, Lake Ashtabula and Lake LaMoure, which flows into Cottonwood Creek, a James River tributary, Holen said.