Invasive Species Zebra Mussels Found in Moss Balls

Zebra Mussels found in moss balls.

There has been news that “Marimo” moss balls sold by PetSmart and Petco are contaminated with Zebra mussels. The report came from an employee of PetCo in Seattle. At this stage, the zebra mussels were found in the pet stores of at least 38 states (March 10th).

The Zebra mussel (Dreissena polymorpha) is a freshwater mollusk from Russia and Ukraine that is hugely harmful outside its native environment. According to the USDA, the Zebra mussel is one of the most invasive and detrimental species plaguing North America.

U.S. and Canadian health officials have acknowledged the issues and are requesting fishkeepers to prevent the spread of the invasive species.

Guidelines by the U.S. Fish and Wildlife Service:


Do not dispose of the moss balls in drains, waterways, or gardens. Moss balls must be destroyed and disposed of in a sealed container in the trash. When following any of the methods listed below, ensure that the disposal method you choose is in compliance with your local state laws and animal welfare regulations.

1. DESTROY 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.

2. 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 of down a household drain —never down a storm drain where it could enter and damage local waterways.

3. DRAIN and clean the aquarium.

Collect any fish or other living organisms and place them in another container, with water from a separate, uncontaminated water source.

Remove contaminated water from the tank and sterilize by adding 1 cup of salt for each gallon of water. Let the water sit for 10 minutes and then dispose of the sterilized water down a household drain.

Clean the aquarium and accessories using ONE of the following methods, ensuring that the decontaminate method you choose is in accordance with manufacturers’ recommendations:

Hot Water Method: Use water that is 120 degrees F to flush and coat the tank and all accessory surfaces for at least two minutes.

Salt Water Method: Make a saline solution using ½ cup of salt per gallon of water and soak aquarium substrate, rocks, décor, and filter media in a saltwater solution for at least 24 hours. Dispose of the treated water in a household drain and rinse all items prior to setting up the aquarium.

Bleach Disinfection Method: Make a disinfection solution using 1 cup of bleach per gallon of water. Soak the aquarium, substrate, rocks, décor, and filter media in the bleach water solution for 10 minutes. Rinse off all items prior to setting up the aquarium. Dispose of the previously used filter media and replace it with new media. Use a dechlorinating product to neutralize any residual chlorine prior to reintroducing aquatic life.

Source: Conservation, U., 2021. Destroy! Don’t Dump! – Zebra Mussel Disposal. [online] Available at: <> [Accessed 12 March 2021].

Leave a Reply