March 8, 2021

MDIFW NEWS: Zebra Mussels Found In Maine Pet Stores, Agencies Urge Eradication, Disinfection Of This Prolific Invasive Species

AUGUSTA, Maine - Zebra Mussels, a highly invasive and prolific species, have been found hitchhiking on aquatic moss balls sold in pet stores in Maine and throughout the country. Maine's natural resource agencies are urging anyone who may have bought these moss balls to destroy them, and for pet stores to remove them from the shelves and destroy them immediately.

Zebra mussels have been found at pet stores in central and southern Maine already, and are likely elsewhere at pet stores throughout the state. If accidentally or intentionally released into the wild, these zebra mussels can quickly outcompete native species, and can clog boat motors, hydropower structures, intake pipes and other in-water structures.

Zebra mussels have been found on moss balls sold as aquarium plants that have names including "Beta Buddy Marimo Balls," Mini Marimo Moss Balls, and Marimo Moss Ball Plant. These moss balls are sold separately but also included in the sale of betta fish.

If you have bought these moss balls, it is important that they are destroyed and properly disposed of immediately, along with disinfecting water if in an aquarium. DO NOT FLUSH moss balls or untreated water down the toilet or dispose of anywhere they could get into a water system.

If you purchased moss balls, destroy them by using one of these methods: 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 - Submerge the moss ball in chlorine bleach for 20 minutes If these moss balls were in a fish tank, the entire tank will need to be disinfected: 1. Remove fish 2. Dispose of all aquatic plants in the same manner as the moss ball, either by freezing or boiling 3. Add one cup of household bleach per gallon of water, mix well, and let sit for at least 10 minutes in the tank 4. Drain the tank and dispose of bleached water down the sink or toilet 5. Thoroughly disinfect (or replace) all gravel, pumps, filters, decorations and other items in the aquarium with a bleach solution (1 cup bleach/gallon of water), letting them soak for at least 10 minutes Again, DO NOT pour tank water down sink drains or flush down the toilet without disinfecting it first. Do not dump untreated tank water anywhere near or into an outside water body, including storm drains.

For more information, please visit

A brief history of Zebra Mussels

Zebra mussels are an invasive, fingernail-sized mollusk that is native to fresh waters in Eurasia. Their name comes from the dark, zig-zagged stripes on each shell. Zebra mussels probably arrived in the U.S. in the 1980s via ballast water that was discharged into the Great Lakes by large ships from Europe. They have since spread rapidly throughout many parts of the U.S but have NOT yet been found in Maine - and it is essential that we prevent them from becoming established in the state. Zebra mussels negatively impact aquatic ecosystems in many ways. Because they reproduce in very large numbers, they filter out enormous quantities of microscopic algae and other nutrients that native freshwater mussels, fish and other aquatic species need for food. They form dense beds attached to the bottom substrate and other hard surfaces, including the shells of native mussels competing for space and even smothering native mussels and other bottom dwelling organisms by their sheer numbers. They also cause great economic harm by attaching to and clogging boat motors and hulls, docks, hydropower structures, intake pipes for water treatment and power generating plants, and other in-water structures, which can cost millions of dollars to remove and repair the damage. Their huge populations can also greatly reduce lakeshore property values. Zebra mussels are a restricted/prohibited species in Maine. For more information on Zebra mussels, please visit:

For more information, please contact the Maine Department of Inland Fisheries and Wildlife, The Maine Department Agriculture, Conservation and Forestry, and the Maine Department of Environmental Protection.