Invasive zebra mussels found another avenue for potential infestation of Montana waters. Montana Fish, Wildlife & Parks was notified Wednesday that zebra mussels were detected in aquarium moss balls sold at a pet store in Washington state. FWP immediately checked pet stores around Montana and found invasive mussels in moss balls at multiple locations.  

It appears these moss balls were imported from Ukraine to a distributor in California and were shipped to pet stores nationwide. The facility that imports the moss balls has been quarantined and all shipments of moss balls have been stopped.  

A moss ball is a species of green algae that is formed into a ball and is 2 to 5 inches in diameter. Moss balls are purchased for home aquariums to help absorb harmful nutrients in the water and limit the growth of undesirable algae. 

All of the mussels detected in Montana so far have been dead shells. However, live mussels were found on moss balls in Oregon and Idaho. 

FWP is working closely with other states and federal agencies to address this nation-wide issue.   

If you have recently purchased moss balls, remove them from the water, place them in a plastic bag, and put them in the freezer overnight. Additional guidance for addressing potential mussels in aquariums and how to treat tank water will be available soon. Please don’t dispose of your aquarium tank water in your household drain.  

This is another reminder to never dump aquarium tank pets, plants, or water into Montana’s waterways.  

• It is illegal to release fish and other aquarium pets into natural waterways. If you can’t keep your pet, find someone else who can adopt it, turn it in to a pet store or humane society, or euthanize it. 

• Aquarium plants can impact native aquatic plant and animal species. Let unwanted plants dry and then dispose in the garbage.  

• Aquarium water can harbor pathogens and diseases. Dispose of tank water on the ground away from waterways.  

Visit Don’t Let It Loose  https://www.dontletitloose.com/ 

If you have any questions call the Aquatic Invasive species hotline: 406-444-2440.