Oregon bans import of aquarium accessory infested with invasive zebra mussels

Marimo or Moss balls showed up in pet stores; tips offered for removal

SALEM, Ore. (KTVZ) -- The Oregon Department of Agriculture said Monday it has filed emergency rules prohibiting the import of Marimo or Moss balls infested with invasive zebra mussels.

According to the rule, moss balls may only be imported to Oregon if accompanied by a quarantine compliance certificate stating the commodity was inspected and found free of zebra mussels, issued within seven days of shipment. Moss balls without proof of inspection within the seven days will be destroyed.

The invasive and destructive zebra mussels showed up in imported aquarium accessories across 32 states including Washington and Oregon. In March, the Oregon Department of Fish and Wildlife confirmed zebra mussels were found inside an aquarium product called Marimo ball moss plants, sold in pets stores across the state, including Salem and Ashland.

“The detection of zebra mussels in Oregon is very serious, and the state is taking strong action to protect our waterways and agriculture,” says Dr. Helmuth Rogg, ODA's director of plant protection and conservation programs. “These striped little mollusks can breed and establish themselves quickly threatening native fish and wildlife by consuming available food and smothering native species, destroying entire ecosystems.”

Once established in lakes, reservoirs, or waterways, zebra mussels attach to hard surfaces, causing blockages to mechanical systems, including irrigation and public works canals, costing taxpayers millions of dollars in damage. It is estimated that zebra mussels cause at least $1 billion per year in damages and associated control costs throughout the United States' infested region.

Oregon’s emergency rule is effective immediately. Violation of this emergency quarantine may result in civil penalties of up to $10,000, as provided by ORS 570.995.

ODFW staff are contacting local businesses that carry pet products to determine if they sold or are selling zebra mussel infested products. 

Moss balls can be safely destroyed either by freezing or boiling before disposing of it in the trash. Do not flush the moss ball down the toilet or throw it outside as mulch. 

The aquarium needs to be disinfected after the moss ball is destroyed. After removing the fish, apply household bleach (one cup of bleach per gallon of water) and let it set for ten minutes before disposing of water down a sink or toilet. Also disinfect filters, gravel and structures with a solution of bleach before disposing of the water down the toilet.

If the aquarium size or other reasons make it difficult to disinfect a tank, it is recommended that you disinfect the water with bleach when conducting a water exchange in the tank before disposing of the exchanged water.

For information on how to safely clean your aquarium and dispose of the moss balls please watch ODFW’s how-to video.