Aquarium owners: Dispose of “moss balls”

WGF 3-9-21

Wyoming aquarium owners are urged to remove “moss balls” from their tanks and boil the plant and any tank water before properly disposing. Moss balls of many varieties meant for aquarium decor have been found to carry zebra mussels. Zebra mussels are an aquatic invasive species (AIS) and can cause severe damage to municipal water systems and natural waters.

“If you have moss balls in your aquarium, please remove them right away. Take care not to flush the moss ball, pour any aquarium water into drains or nearby waters sources like a local pond or a creek. You could spread zebra mussels,” said Josh Leonard, AIS coordinator for Game and Fish.

To dispose of moss ball and all aquarium water:

  1. Remove any pets from the water and tank.
  2. Remove the moss ball, other plants and any water from the aquarium and put them into a heat-safe pot. Do not dispose of any water down the drain or toilet.
  3. Inspect the moss ball and tank for zebra mussels and if you find any contact your local Game and Fish regional office or local warden.
  4. Boil the moss balls, plants and any water it’s been in contact with for at least five minutes
  5. Dispose of the moss ball and other plants in trash. 
  6. Pour out the boiled water on a semi-permeable surface. That could be a houseplant or outside — like grass or soil — that is not located near standing water or a storm drain.

Other aquarium decorations need to be cleaned in boiling water and dried completely before they can be used again. BE CAREFUL NOT TO POUR ANY WATER DOWN DRAINS IN THIS PROCESS. Game and Fish uses a similar approach to clean watercraft.

Leonard said all moss balls should be removed and destroyed. 

“At this point, there is no way to tell which moss balls could have zebra mussels by a date or a brand. All aquarium owners should destroy moss balls. Do not buy new moss balls to add to your tank and never pour aquarium water or products into any natural waters,” Leonard said.

Game and Fish has an anonymous tip line where the public can make reports if they know of anyone releasing fish or aquarium plants and water in Wyoming’s waterways to help Game and Fish with monitoring efforts. This line can also be used to report if you have done this yourself. Report instances to the Stop Poaching hotline at 1-877-WGFD-TIP (1-877-943-3847) or 1-307-777-4330 for out-of-state calls or online.

Wyoming is one of over two dozen states across the US to identify zebra mussels in pet and aquarium stores in connection to moss balls. The Department is working closely with other states and Federal agencies to address this nationwide issue. Game and Fish is urging any stores to immediately remove this product from shelves.

Anyone who finds zebra mussels in their tank must call the local Game and Fish regional office or game warden so a representative can collect the sample. For more information, visit