Invasive Zebra Mussels Found in Aquarium “Moss Ball” Product in Pet and Aquarium Supply Stores

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AUSTIN – The Texas Parks and Wildlife Department (TPWD) and other wildlife agencies around the country are urging stores who sell aquarium products to remove a “moss ball” aquarium plant product from their shelves and for customers to dispose of the contaminated product after invasive zebra mussels have been found hitchhiking on these products in states around the country, including Texas.

These “moss balls” are a species of algae that form green balls up to a few inches in diameter and are sold as an aquarium plant under names such as “Beta Buddy Marimo Balls,” “Mini Marimo Moss Balls,” and “Marimo Moss Ball Plant.” They may be sold separately or provided with the sale of Betta fish. These moss balls are believed to have been imported from the Ukraine and distributed across the continental U.S.

Zebra mussels can be recognized as small shellfish with triangular, brownish shells, often with their namesake zebra stripes, that may be attached to or growing inside the moss balls. They are very small, growing to no more than an inch in size, and the individuals found on the moss balls in Texas were less than a quarter of an inch long.

“Petco stores have been working diligently to remove these products from their shelves and I have informed PetSmart of the presence of zebra mussels within this product,” said Jarret Barker, TPWD Assistant Law Enforcement Commander. “We urge any other pet and aquarium or retail store selling these ‘moss balls’ to remove this product from shelves and discontinue future sale.”

Aquarium owners are urged to stop buying this product and to safely dispose of any that have already been purchased. This can be done safely by completely drying, freezing, or placing the moss balls into a plastic zipper bag and then disposing of it in a garbage bag. Aquarium water should be replaced, and filters/cartridges replaced or disinfected. Aquarium water can be disinfected prior to disposal by adding one cup of bleach per gallon and allowing it to sit for 10 minutes before disposing the water down the drain. This method can also be used to disinfect gravel, filter, and other structures, and is highly recommended if zebra mussels are found attached to the moss or in the aquarium.

Zebra mussels are highly invasive, causing economic and ecological damage when released into the wild, and these aquarium products pose a risk of this species being introduced into new water bodies in Texas and causing serious harm.

“Zebra mussels have already been introduced into many Texas lakes and are causing changes to the ecosystem along with damage to boats, water supply and control infrastructure,” said Brian Van Zee, TPWD Inland Fisheries Regional Director. “It is important that we take all possible precautions to prevent them from being introduced elsewhere.”

Aquarium dumping is a well-known pathway for introduction of aquatic invasive species as well-meaning pet owners release unwanted pets, unintentionally causing harm to native fish and wildlife. This includes not only the fish, but also aquarium plants and organisms like the zebra mussels that may be hitchhiking on these plants. Aquarium owners are urged to never dump their tanks and to learn more about alternatives to aquarium dumping by visiting the TexasInvasives website.

“Invasive species such as these zebra mussels and snails can hitchhike in aquatic plants sold for aquarium use,” said Monica McGarrity, Senior Scientist for Aquatic Invasive Species. “It is important for staff at stores as well as customers to always check aquarium plants for hitchhiking organisms and to alert store management and not sell or buy plants with mussels, snails, or other organisms attached.”

To learn more about zebra mussels and other invasive species in Texas, visit the TPWD Stop Invasives website.