MDC says don't dump aquariums to avoid spreading invasive species

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Kansas City
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Kansas City, Mo. – The Missouri Department of Conservation (MDC) says with care citizens can help avoid the spread of harmful invasive species. One way, do not dump aquariums in rivers, ponds, and lakes. A non-native fish recently found at Blue Springs Lake in the Kansas City area provides an example.

A bass angler caught a tropical, 10-inch oscar fish on a crankbait while fishing at the lake. Although the head and mouth somewhat resembled a bluegill, the tail, fins, and coloration did not resemble a native Missouri fish. An MDC fisheries management biologist identified it as a type of oscar fish kept in aquariums. This fishes’ native habitat is tropical South America. Oscars are members of the cichlid fish family.

This oscar will not survive Missouri’s cold-water temperatures in winter, said Jake Colehour, MDC fisheries management biologist. But many non-native aquatic plants and fish kept in aquariums can survive and become invasive. They often out compete natives for food and habitat because they don’t have native predators or foragers. Undesirable non-native fish can crowd out sport fish or baitfish they feed on. They can also spread disease to native fish. Invasive aquatic plants can completely choke a pond, river, or lake, harming native fish and making those waters difficult for use by anglers, boaters, and swimmers.

Often an aquarium fish will outgrow its tank, or the owner will get tired of caring for it. They decide to dump the fish and plants into public waters rather than proper disposal. This creates potential environmental hazards. Aquarium dumping is illegal and especially a problem in urban areas. Alternatives are available.

Stores that sell aquarium fish will often take them back. Check the internet for aquarium clubs in your city. They often have members that will take unwanted fish and plants. Humanely euthanizing the fish by placing it in icy water to slow and stop its heart before disposal in the trash is also an alternative.

Also, anglers should not dump bait buckets into lakes or rivers. Pour them out away from the water on shore or save the bait for another trip. Dumping bait buckets is a way invasive fish or crayfish can be moved into new waters.

For more information about invasive species in Missouri, visit