FOR IMMEDIATE RELEASE:                                CONTACT: Gail Mastrati, 401-255-6144

Tuesday, March 9, 2021                                                                This email address is being protected from spambots. You need JavaScript enabled to view it.






PROVIDENCE, R.I. – The US Fish and Wildlife Service (USFWS) has alerted the Department of Environmental Management (DEM) that the Zebra mussel, a highly invasive aquatic invertebrate, may have been distributed to pet shops in Rhode Island. Zebra mussels (Dreissena polymorpha), regarded as one of the most destructive invasive species in North America, have been found in “moss balls,” an aquarium plant product sold at aquarium and pet supply stores nationwide. A moss ball is a species of green algae that is formed into a ball and is 2 to 5 inches in diameter.


Zebra mussels can quickly take over once they get established in a waterbody and cause significant damage including disrupting the food chain, changing the chemistry of the water (which can cause more blue green algae outbreaks or offensive taste), and clogging water intake and delivery systems. DEM is concerned that live mussels released into a storm drain or flushed could be introduced into a waterway.


“DEM is advising pet shops that have these products not to sell them and consumers who have recently purchased moss ball aquatic plant products not to use them,” said Scott Marshall, DVM, RI State Veterinarian. “We urge consumers not to dispose of the moss balls in drains, waterways, or gardens. Moss balls must be destroyed by freezing, boiling or bleaching them and disposed of in a sealed container in the trash. Live mussels released into a storm drain or flushed could be introduced into a waterway.”


On March 6, DEM notified more than 50 pet shops, fish and aquarium retailers, and big box stores of the possible contamination and asked that they remove the following products from their shelves: Plant Ball Japanese Marimo, Betta Buddy Marimo Ball, Betta Buddy Baby Marimo Ball, and Moss Assorted Shrimp Buddies.


Destroy, don’t dump

USFWS has issued guidance to consumers on how to destroy and dispose of the moss ball and zebra mussels. Click here. Moss balls should be destroyed in one of three ways:


  • Freeze – place the moss ball into a sealable plastic bag and freeze for at least 24 hours.
  • Boil – place the moss ball in boiling water for at least 1 full minute.
  • Bleach / Vinegar – submerge the moss ball in chlorine bleach or undiluted white vinegar for 20 minutes.


Consumers should dispose of the moss ball and any of its packaging in a sealed plastic bag in the trash. If vinegar, boiling water, or bleach was used, the liquid can be disposed down a household drain —never down a storm drain where it could enter and damage local waterways.


Fish tank owners should drain and clean the aquarium after moss balls have been removed. Collect any fish or other living organisms and place them in another container, with water from a separate, uncontaminated water source. Sterilize the contaminated aquarium water by adding ¼ teaspoon bleach for each gallon of water. Let the water sit for 10 minutes and then dispose of the sterilized water down a household drain.


Zebra mussels are small, fingernail-sized mollusks native to the Caspian Sea region of Asia. They have three life stages – larval, juvenile, and adult. In the microscopic larval stage, the mussels live freely in the water column, allowing them to be easily transported. Adult zebra mussels can stay alive for several days outside of water and are common hitchhikers on boats, fishing equipment, and aquarium plants. Despite their small size, zebra mussels grow quickly and form colonies that can clog pipelines used for water filtration, render beaches unusable, and damage boats and infrastructure. They also impair aquatic ecosystems by harming native organisms.


Additional information and recommendations on handling zebra mussels is available at Zebra Mussel Disposal ( []


The possession of zebra mussels is prohibited in Rhode Island under Section 3.17 of Rules and Regulations Governing the Importation and Possession of Wild Animals, which can be seen here,


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