A mussel and aquarium moss found in Wyoming this week. (Wyoming Game and Fish Department)

The Wyoming Game and Fish Department has found destructive invasive zebra mussels in aquarium moss sold in pet stores and is making their removal a priority.

The department received an email Wednesday from another state’s wildlife agency warning of the moss balls sold by Petco, Alan Osterland, Game and Fish fisheries chief said.

With the alert, “we thought we better check some pet stores here,” he said. Agency workers fanned out in search of “marimo balls” or moss balls.

“We hit all the Petco and PetSmart stores in the state,” he said. Inspectors found the moss — a green filamentous algae — in Cheyenne, Rock Springs, Casper, Sheridan and Gillette and removed it.

In the moss, aquatic invasive species specialists discovered three mussels — believed to be zebra mussels. One specimen was a partial shell and not viable.

“We’re not the only state that’s finding them,” Osterland said. “It’s growing every day.” By Thursday officials had found contaminated moss in more than 20 states, Osterland said.

Exotic zebra mussels reproduce rapidly, take over native ecosystems, wreak havoc on waterworks and remove nutrients from lakes, streams and reservoirs. Wyoming has kept invasive mussels out of state waters in a years-long aquatic invasive species program that’s mainly focused on inspecting boats.

“Obviously, this puts a different light on it,” Osterland said of department priorities. For the immediate future, the AIS campaign is focused on aquariums and moss.

It’s important that people who might have moss balls in an aquarium tank closely follow Game and Fish instructions for removing and cleansing the moss and aquarium water, he said.

Moss came from Ukraine

The moss balls in question came from Ukraine, Osterland said, and were supposed to have been shipped after being dried out. Consumers are supposed to rehydrate the product, which oxygenates water in tanks. 

“This is a plant — an algae — so it’s going to need to have some moisture,” Osterland said. “When [stores] get this product, it always comes moist. It’s probably moist when it is being shipped, which is concerning.

A zebra mussel found in aquarium moss in Wyoming this week. (Wyoming Game and Fish Department)

“Everybody looks at it as definitely a serious threat,” he said. “Petco has been real responsible — they got on it pretty quickly, removed it from shelves.”

The U.S. Fish and Wildlife Service is also involved in what amounts to a nationwide alert, he said.

Anyone with marimo moss or moss balls should remove fish and turtles from the aquarium in question and carefully dispose of the water as recommended. The moss and aquarium water should go into a heat-safe pot.

Do not pour any water down the drain or into a toilet, Game and Fish says. Mussels can be virtually invisible in their immature stage when they are called veligers.

Inspect the moss and tank for mussels. If you find any, call Game and Fish.

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Boil the marimo balls, plants and water for at least five minutes. Dispose of the marimo ball and other plants in the trash. Pour the boiled water onto a semi-permeable surface that’s not near standing water or a storm drain.

Prompt action may keep Wyoming mussel-free from this particular threat, Osterland said. “Hopefully, the cat’s not out of the bag.”

Angus M. Thuermer Jr. is the natural resources reporter for WyoFile. He is a veteran Wyoming reporter and editor with more than 35 years experience in Wyoming. Contact him at angus@wyofile.com or (307)...

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  1. Bad thing about these Muscles are they can get into everything we been fighting against them here in our Missouri Lakes the last 15 years or better. Just make certain people clean the bottom of their boats they put into the lakes up there and check your wading boots also. Good luck