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Preventing the Escape of Exotic Aquarium Species

The days are shorter now and the chill in the air makes summer feel like a distant dream. During these dark and blustery days, many people spend a greater amount of their time indoors and turn their energies towards home decorating, including the addition of a bright, colorful aquarium. Pet stores state-wide experience increased sales of aquariums and supplies during the winter, especially over the holiday season. If you are among the throngs of people who either own an aquarium or wish to brighten your home with one, there are several things to consider.

Many aquarists prefer a basic aquarium consisting of gravel, decorative artificial plants and fish. This set up requires minimal technical understanding and is fairly easy to maintain. Other hobbyists enjoy the challenge of including live aquatic plants in their tank. Live plants add oxygen to the water, absorb nutrients, provide hiding areas for fish and create a very realistic and natural environment. The downside is that living plants are more difficult to deal with than their plastic counterparts, due to very specific light and water chemistry requirements.

If you decide to include live plants in your aquarium, it is best to select native species. Native species are plants or animals that have evolved in a specific region and are part of the original flora and fauna of the land. Unfortunately, many of the most popular aquarium plants have been imported from other regions of the world, and are considered exotic or non-native. Some of these species pose a serious risk for the environment if they are released. Since they are new to the area, they have not evolved predators or biological controls to keep their populations in check, and as a result many of these species become invasive. Invasive species are plants or animals (native or non-native) that are able to invade and completely alter an aquatic ecosystem, drive out native species and dominate the area.

If you decide that you really wish to include non-native live plants in your aquarium, avoid species that are known to easily become established and quickly degrade Massachusetts ' waterways. Some infamous aquarium exotic species that fit into this category include South American Waterweed ( Egeria densa ) and Fanwort ( Cabomba caroliniana ). There are several non-native species that are not believed to be able to survive in Massachusetts.

Many exotic and potentially invasive aquarium plants are sold under alternate names. South American Waterweed is often called Anacharis, Elodea and Brazilian Waterweed; and Variable Milfoil is frequently sold as Milfoil sp, or Red Foxtail. When you visit your pet store bring a guide with you to aid in positive identification. For a free Guide to Selected Non-Native Aquatic Species in Massachusetts contact the Lakes and Ponds Program or download a version from the Lakes and Ponds website.

There are several common native species sold at pet stores that are beautiful additions to an aquarium. These include Coontail ( Ceratophyllum ), Water Celery ( Vallisneria americana ) and Common Waterweed ( Elodea ).

At some point you may no longer wish to maintain your aquarium. NEVER EVER empty your aquarium into a lake, pond or stream! The plants, even fragments, can become established and completely destroy the lake or pond. Although many tropical fish do not survive for long in the wild, others can reproduce rapidly and prey on native species. The unintentional release of the notorious Snakehead fish into Crofton Pond in Maryland required that the entire waterbody be poisoned with Rotenone to kill all the fish. This was a necessary precaution as the snakehead fish ( Channa micropeltes) can breathe air, walk on land to other waterbodies, reproduce rapidly, has a voracious appetite, large teeth and grows to over 3 feet. Although only a single two-foot fish was released in 2000, over 1000 juveniles and six adults were recovered in 2002 after the treatment. Unfortunately, every fish in the lake perished as a result of one person's mistake.

Some aquarium fish can appear healthy but harbor diseases or parasites that wild species are not immune to.

While invasive plants aren't this scary, some species can spread rapidly and significantly degrade a waterbody. The dense mats of vegetation often impair or prevent swimming and boating and other recreational activities. In addition, the aesthetic appeal, biodiversity and property values may quickly decline. Once invasive plants are established they are almost impossible to eradicate and very expensive to control. The best method of protection is prevention.

Protect the environment and consider donating your aquarium to a school, nature center or nursing home, or giving it to friends and family. Alternatively, try selling your aquatic set up in the Want Ads or local newspaper, as there may be people in your area who are interested in acquiring an established aquarium. Lastly, you can try to return your fish to a local pet store. Although many stores will not accept pet fish, there are a few locations with the ability to quarantine a new fish for a period of time before placing it in a regular display tank for resale. Live plants can be safely disposed of by placing them in plastic trash bags and remaining aquarium water can be emptied down the toilet. For more information or a free brochure on invasive species contact the DCR Lakes and Ponds Program. For information on marine invasive species or a free brochure on invasive aquatic pets contact the Costal Zone Management.