March 2021

The Alaska Department of Fish and Game (ADF&G) has recently learned that the highly invasive aquatic species, zebra mussels (Dreissena polymorpha), were shipped to Alaska attached to marimo moss balls. Live moss balls are often sold at pet or aquarium supply stores as decorations in fish tanks. If you have recently purchased moss balls please inspect them and your aquarium for any signs of zebra mussel presence. If zebra mussels are found, please do not dispose of aquarium contents by pouring down the drain or flushing – this can cause serious issues with home plumbing and can release the invasive species into the environment.

Never dump aquarium contents into the wild or into a storm drain. Prevent the spread of aquatic invasive species!


Zebra mussels are a freshwater shellfish about the size of a thumb. They can quickly colonize a freshwater ecosystem and once established it’s nearly impossible to eradicate. They can grow densely and encrust fish passage facilities and aquaculture operations as well as deplete plankton and disrupt native food webs.


Read the 3/4/21 press release from ADF&G and an article in the Cordova Times for helpful information on this new threat to Alaska.

For more information on how to identify zebra mussels, how to dispose of zebra mussels, and how to
report zebra mussels or other invasive species, please contact: Tammy Davis, ADF&G Invasive Species
Program coordinator: or (907)465-6183.