Moss ball - zebra mussels wb.jpgZebra mussels.jpg

Left: Moss balls like this one containing an invasive zebra mussel have been found in pet stores in 21 states. Zebra mussels are an aquatic invasive species (AIS) that can cause environmental and economic harm. Right: During a National Water Quality Network sampling trip in May 2018 to the St. Lawrence River, hydrologic technician Dave Knauer finds a batch of zebra mussels attached to a boat anchor. (U.S. Geological Survey photos)


New York state officials warn aquarium owners about invasive zebra mussels found in ‘moss balls’


ALBANY, N.Y. (March 9, 2021) – The New York State Department of Environmental Conservation (DEC) is urging pet and aquarium stores and consumers to immediately remove and properly dispose of commercially purchased “moss balls” for aquariums after invasive zebra mussels were discovered inside and on some of these products, as reported by the U.S. Fish and Wildlife Service. Consumers should be advised that moss ball products purchased from PetSmart and Petco may be subject to a voluntary product recall.

Zebra mussels are an aquatic invasive species (AIS) that can cause environmental and economic harm. Several species of algae comprise moss balls, which are two to five inches in diameter. Zebra mussel larvae are so small that people cannot see them. If released, these larvae can cause great harm to waterbodies.

Consumers are advised to remove and properly dispose of any moss balls purchased within the last year by following these steps:

• Dispose of moss balls removed from tanks in a sealed garbage bag. Other aquarium plants also should be disposed of as they may harbor zebra mussels.

• To disinfect a tank after safely removing any animals, apply household bleach — one cup of bleach per gallon of water — and let it sit for 10 minutes before disposing of water down the sink or toilet.

• Disinfect filters, gravel, and structures with a solution of bleach. Water from filters must also be treated with household bleach before disposing of water down the sink or drain.

• For larger tanks that cannot be easily drained, email for instructions.

• If zebra mussels are in a tank or on a moss ball, take a photo if possible and report the observation via email to, or by phone, (518) 402-9405.

• Be advised, just because zebra mussels might not be seen does not mean their larvae are not present.

Zebra mussels can quickly take over once established in a waterbody. These invasive pests will disrupt the food chain, change water chemistry, and clog water intake and delivery systems for drinking water, irrigation, and hydro power. Live mussels released into a storm drain or flushed could be introduced into a waterway, starting a new population and causing significant damage.

AIS are non-native aquatic plants and animals that can cause environmental and economic harm, as well as harm to human health. New Yorkers can help protect the state’s waters by preventing AIS from entering lakes, rivers, and ponds from aquarium releases. To find more information about DEC’s guidelines for aquarium and pet owners, visit

Invasive species are plants, animals, insects, and pathogens that are not native to an area and cause harm to the environment, agriculture, the economy, or human health. All New Yorkers can support the fight against invasive species by helping to locate and map infestations, using only local firewood, using Clean Drain Dry techniques to properly clean watercraft before and after boating, making informed choices for aquariums and aquatic gardens, and removing invasive species from the yard. To learn more about AIS, go to the DEC website


(New York State Department of Environmental Conservation)