TPWD reports zebra mussels found in aquarium moss balls in stores

The Texas Parks & Wildlife Department says that invasive zebra mussels have been found in moss ball products for aquariums in states across the country, including Texas.

TPWD and other wildlife agencies are urging pet and aquarium supply stores to pull the products from their shelves and customers to dispose of the product.

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

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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, says TPWD.

"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."

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TPWD is urging aquarium owners to stop buying this product and to safely dispose of any already purchased 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 also 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 of 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. TPWD says these aquarium products pose a risk through aquarium dumping, where 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.

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Aquarium owners are urged to never dump their tanks and to learn more about alternatives to aquarium dumping by visiting the Texas Invasives website.

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